Meet the Mantis Shrimp

Let me introduce you to one of our favorite marine creatures: the mantis shrimp. Why are they a favorite? They're cute (sort of), they're very smart (for a crustacean), and they're fun to watch. Unfortunately, they're also difficult to photograph -- more on this a little later!

The individual in the photos on this page is a Shortnose Mantis Shrimp (Odontodactylus brevirostris), from Hawaii. I know that the critter looks pretty big in these photos, but it's not. These are macro images. The mantis shrimp in these pictures was only about two inches (5 cm) long. You can click on any of the photos to see a larger view.

Despite the name, mantis shrimps are not true shrimps. I guess I don't need to explain that they are not mantises, either -- although they apparently acquired their name because they resemble praying mantises somewhat. Like crabs and lobsters and true shrimps, mantis shrimps are Crustaceans.

All mantis shrimps belong to the order Stomatopoda. Stomatopods have a number of features that set them apart from other crustaceans. Among the most notable -- and noticeable -- are their raptorial arms, and eyes that are highly evolved.

Mantis Shrimp Eyes

I've always wondered what the undersea world looks like through the mantis shrimp's eyes, because their eyes are like no other eyes. Take a look at the photos, and notice that the eyes are set at the end of stalks. Each eye is independently movable -- and they seem to move constantly, giving the critters a hyper-alert look. Each eye is trinocular, that is, each has three separate perceptual regions. This would be sort of like having built-in trifocal lenses, except that instead perceiving things at three different levels of magnification, each eye region is specialized to perceive a different kind of visual information -- but all at once.

Mantis shrimp eyes are capable of hyperspectral vision. In other words, not only can they see the visible light spectrum, like we can, but they also can see spectra of light that we cannot, including infrared and ultraviolet. Very recently it was discovered that mantis shrimps have the ability to perceive circular polarized light, too.

Raptorial Appendages

The mantis shrimp's raptorial appendages actually are legs that have evolved into claw-like arms, specialized for killing prey. There are two types: some species have thin, barbed raptorial arms that can spear prey; others have club-like raptorial appendages that smash their prey. (The mantis shrimp species in the photos is a 'smasher'.) When mantis shrimps are at rest or walking about, they keep those killer appendages folded up like closed jack-knives against their bodies, just as the creature in these photos is doing. When they go after prey, those appendages unfold at an incredible speed and they spear or whack the prey.

The spearers tend to choose soft-bodied prey like worms and little fish. The spearers are ambush predators. That is, they sit quietly and concealed until prey comes along and then they attack. In contrast, the smashers usually pursue their prey -- and that is one of the mantis shrimp behaviors we love to watch, when we get the chance.

The smashers use their raptorial arms not just to kill prey, but also to break it apart to eat. The species in the photo eats things like small crabs, and gastropod snails that live in shells. When the mantis shrimp sees one of those and goes after it, first he punches it silly, then he uses his raptorial arms to crack open the shell so that he can pick out the meat with his little forward legs, which are also specialized for that purpose.

The Star of the Puako 'Petting Zoo'

The mantis shrimp in the photos on this page lives off the coast of Puako, Hawaii in an area where we have made countless dives. When you dive in the same area again and again and again over a period of years, you become aware of things that a visiting diver probably never would notice in the course of just a few dives. One thing you learn is where all the different types of creatures live. Except for pelagics that roam the open sea, most marine creatures have a relatively small range. Once you spot where they live, you can usually count on seeing them in the same general area any time you go there. Once you know where to look, there they will be.

Puako has a wonderful fringing reef that parallels the shoreline for a couple of miles. The coral reef area is beautiful, and very accessible, but there are areas beyond the reef that are just as fascinating, if not quite so pretty. Where the seaward edge of the reef ends there is a steep slope. The top of the slope has many rocks and is still covered with quite a lot of coral, but deeper on the slope where less sunlight penetrates there is little live coral. There are more rocks, plus lots and lots of coral rubble -- lumps of dead coral washed down the slope from the reef over time. At the base of the rubble slope the terrain levels out into a sandy plain.

There is an area near the base of the rubble slope, at a depth of about 100 ft (30 meters), that we named the Petting Zoo. We called it that because it teems with small creatures. Sometimes we would go directly to the Petting Zoo, plop ourselves down in one spot, and spend the entire dive watching all the little creatures go about their business. You can learn a lot about marine creatures' behavior that way.

On one of our visits to the Petting Zoo, we noticed this particular mantis shrimp. Some mantis shrimp species are nocturnal, i.e. they only come out at night. This species works the day shift. We first saw him when he emerged from his burrow and began scurrying about. Mantis shrimps can swim a bit. If you look at the second photo above, you'll notice that this creature has a tail not unlike that of a lobster. They can use their tails to propel themselves through the water for short distances, but their more usual method of locomotion is to run about. Notice I said run. They move quickly -- usually too quickly to get a good macro shot.

Mantis shrimps live in burrows. This one had excavated a double-ended tunnel under the sand. I have no idea what it's like inside the burrow -- we used to joke that he probably had an overstuffed chair and a TV in there for all we knew. We did notice that outside the entrance to the burrow we would sometimes see pieces of broken shell in little piles. A few times we saw the critter in the process of housecleaning -- literally throwing bits of shell out the door.

On successive visits we saw this mantis shrimp stalk and kill prey -- usually a small crab. One time we saw him smack a crab that was bigger than he was, dismember it, and drag the body to the opening of his burrow. The mantis shrimp disappeared inside the burrow for a few minutes, then re-emerged and whacked the shell of the now legless crab a couple of times to crack it open and began to dig out the 'meat' for his feast. We watched him until it was time for us to begin our ascent. He was still working on the crab when we left. When we came back a day or two later we looked for the remains. Sure enough, there was a recognizable piece of the crab's empty shell not too far away from the entrance to the mantis shrimp's burrow.

I mentioned in the first paragraph of this article that mantis shrimps can be difficult to photograph. That's because they seem to be in motion constantly when they are outside their burrows. It's not too difficult to get a shot of one peeking out of its burrow, but capturing an image of the whole animal had eluded me for years.

Then one day at the Puako Petting Zoo, this little mantis shrimp came out of its burrow and just stood there looking at us. And -- Hallelujah! -- not only did I have my camera, it was set up for macro photography. Moving as slowly as I could, not to startle the critter, I lay down on my belly on the sand at the edge of the rubble slope, and sort of inched toward the mantis shrimp. He didn't run away.

I focused carefully on his wonderful eyes and pressed the shutter release, figuring this would probably be my one and only shot. So often in underwater nature photography, the flash of the strobe startles a photo subject and it quickly leaves, so one shot is all you get. But no, not this mantis shrimp. I expected him to high-tail it to his burrow, but instead he actually came toward me a bit, stopped and turned sideways, almost posing. Now practically touching him with the end of the lens port, I took another shot, and a third.

Then he turned the other way and positioned himself as if to say, "How's this? Can you see my tail a little better now?" I shot once more, and then he finally scampered over to his burrow and disappeared inside. I did press the shutter one more time while he was in retreat, but his movements had stirred up the sand by then.

I've often wondered what it was that made that mantis shrimp decide to be such a cooperative photo model that day. I've never again had an opportunity like that.

What Brutus the Great Barracuda Saw

In the previous post I wrote about a Great Barracuda named Brutus who liked to follow Jerry around the reef at Puako. If you read that post, you'll recall that after a few experiments, we concluded that the big fish actually was attracted to the yellow sleeves on Jerry's wetsuit, probably because the color stood out so well against the background, compared to the black and dark blue suits the other divers in our group were wearing.

Today I was looking through some recently scanned photos, and by chance I came across this nice shot of Jerry with a school of Horse-eye Jacks. I took it with natural light -- no flash -- at Providenciales in the Turks and Caicos Islands. Looking first at the thumbnail, I thought, "This looks like a Right Blue photo." But when I enlarged it on my monitor, I knew instantly: "THIS is what Brutus saw!"

See what I mean? (Insert 'big grin' emoticon, heh heh.)

[Click on the photo to enlarge]

Remembering Brutus, the Great Barracuda

You would think that after doing thousands of dives at hundreds of dive sites around the world, we would not remember encounters with individual fish. Who knows how many different fish we have seen in our long years of diving? Yet there are a few individuals among the masses that do stand out in our memory. One of those was a big silvery fish that hung out near our home reef at Puako, Hawaii for the better part of a year.

That big silvery fish was a Great Barracuda (Sphyraena barracuda), just like the one in the photo at right. I photographed that one in the Caribbean, but we have seen this species all over the world, and have had many close encounters with them. Most of our encounters with barracuda were unremarkable, until we crossed paths with the one we came to call Brutus.

Brutus the Great Barracuda was 'great' in more ways than one. He was great in size: we figured he was about five feet long and probably weighed around 70 pounds. He also was a great companion: if he spotted us from a distance he'd hurry to us, and then follow us around for most of our dive.

Seeing a big barracuda like Brutus underwater can make the hair on the back of a diver's neck stand up and prickle, but Brutus never harmed us, nor did he ever give any sign that he wanted to do anything more than watch what we were doing. In fact, he could be downright nosy.

Usually Brutus followed us at a respectful distance of, say, 20 to 30 feet. But there were times when we'd stop to look closely at some tiny little creature, and that distance would close until we'd have Brutus looking right over our shoulders. I don't know why he did that. Maybe he thought we might have found something good to eat, and he didn't want to miss it. What I do know is that sometimes we'd turn our heads, and there would be this big barracuda face with the gnarly-toothed grin right there!

When Brutus first started to follow us around, we thought maybe we were imagining it. We thought maybe the big fish just happened to be going where we were going, and was not really following us at all. So, along with our friend Dan, we cooked up an experiment: We agreed ahead of time that if we saw Brutus and he started to follow us, we would reverse direction, swim past him, and see if he then turned around and stayed behind us. He did. After a few more rounds of this we concluded that he really was following us intentionally, and not by chance.

Then we noticed that Brutus seemed to prefer Jerry to Dan and me. When the three of us were diving together, it was our habit to swim more or less parallel to one another, but about 15 or 20 feet apart. We noticed that when we fanned out like that, Brutus would watch all of us, but seemed to follow Jerry more closely. So, we planned another experiment. On one dive, Jerry would be positioned in the middle, with Dan and me at either side. On another dive Jerry would take an end position, and either Dan or I would take the middle spot. Sure enough, regardless of which position in the line-up Jerry took, Brutus would be right behind him.

What was it about Jerry that attracted this big barracuda? The probable answer came one day when I stopped to look at something, while Jerry and Dan swam ahead. When I looked up to see where they were, I spotted Jerry right away. He was wearing a wetsuit that had bright yellow sleeves, and had on yellow fins, too. The yellow was very visible, even from a distance. I couldn't see Dan until I got closer. Dan's suit was all black, just like mine. It was one of those 'lightbulb' moments. "Aha!" I thought. "That's it!" It probably was the yellow in Jerry's dive attire that attracted Brutus.

Barracuda are believed to be attracted to shiny things, probably because much of their diet consists of little silvery fishies. It occurred to me that, while Jerry's fins and wetsuit were not shiny, the yellow color definitely stood out in contrast to the background. You know what's coming, I'll bet. One more experiment.

The next time we went diving, Jerry and Dan swapped suits. Jerry wore all black, and Dan now wore the suit with the bright yellow sleeves. Along came Brutus. We fanned out across the reef, with Dan in the middle, dressed in Jerry's suit. Just as we had hypothesized, Brutus now followed behind Dan. When they switched positions, Brutus still followed Dan. We concluded that it was indeed the yellow in the suit that had attracted the barracuda. After that, we referred to that suit as Barracuda Bait!

So, if you're diving in waters where there are Great Barracuda about, and you don't want to attract their attention, do not wear a high-contrast outfit underwater. Wear a suit that blends, not one that stands out. Don't be barracuda bait.

Crinoids - Also Known As Feather Stars

In the previous post, about our final dives on the wreck of the Zenobia, I mentioned that we saw crinoids inside the shipwreck. As I wrote that, I realized that many readers, and especially non-divers, probably had never seen or even heard of crinoids. They're strange creatures, and I was hard pressed to describe them for that story, so I thought it would be a good idea to show readers of The Right Blue what a crinoid looks like.

The photos on this page show a crinoid known as Klunzinger's Feather Star (Lamprometra klunzingeri), a species found commonly in the Red Sea. This is not the species we saw inside the Zenobia, but these photos should work well to illustrate what a crinoid is like.

Crinoids belong to the same phylum (Echinodermata) as sea stars and urchins. The phylum name means "spiny skinned" and most members of the phylum do have some kind of spiny structures on their outer coverings.

The crinoids have feathery arms, which are jointed. They can (and do) bend every which way. The arms have rows of protrusions, called pinnules, which run the length of the arm, making them resemble feathers. The crinoids catch their food by extending their arms like a fan. Bits of plankton are caught on the pinnules.

These creatures also have a set of appendages, called cirri, that serve as feet. They can move along on the cirri a little bit, but they also use their feathery arms to propel themselves. Sometimes they bend their arms down in a sort of arc, and use them like extra legs to skitter across sand or other flat surfaces. They use their cirri to hold on tightly to whatever they decide to perch upon.

There are teeny tiny hooks on their ends of the cirri, which help them to grab onto their perch. We have seen these actually puncture a sponge enough to leave a scar. I should also add that, on occasion, we have attempted to move a crinoid from one location to another. It's fairly easy to put a gloved finger next to a crinoid's little feet, and nudge it to perch there. The trouble comes in getting the crinoid to release its hold on that gloved finger again!

Crinoids are nocturnal creatures. They fold themselves up into a ball and hide in crevices in the reef during daylight hours. They usually emerge from their hiding places at dusk, and situate themselves on a favorite perch -- on coral, a large sponge, a sea fan -- wherever they can anchor themselves well. Then they unfold their feathery arms and feed all night, returning again to their hiding places at first light.

Crinoids are sensitive to light. When they are exposed to a bright light, they immediately begin to fold in their arms. For this reason, it is sometimes difficult to photograph them in their full glory, with all their arms completely outstretched. Crinoids are fairly plentiful on many reefs, so they are relatively easy to find during night dives. However what often happens is, we shine our lights around and spot a lovely crinoid, but as soon as it senses the light beam it begins to curl up. So, we switch off our lights and wait. Eventually the crinoid will unfold again, but then the photographer is lucky to get more than one or two shots before the light from the camera's strobe prompts the crinoid to fold into itself again. It takes patience to photograph crinoids.

The two photographs on this page were shot in quick succession. In the first photo, the crinoid's arms are fully extended. (Take note of its little cirri, hanging onto the coral it has chosen as a perch.) In the second photograph, the crinoid already is reacting to the light emitted by the flash during the first shot, so it's beginning to curl up. I photographed this crinoid during a night dive in the Red Sea, off the coast of Egypt's Sinai Peninsula. [Click on the photos to enlarge.]

Wordless Wednesday #20 - Happy Valentine's Day

[Click photo for larger view.]

My previous Wordless Wednesday posts.

Wordless Wednesday home page.

Do Not Disturb: Sleeping Fish

We all need our rest, and so do the fish in the sea. Fish don't sleep exactly like we do. For one thing, they don't have eyelids, so they can't close their eyes. Nevertheless, most fish we know about do take their rest for some part of the day or night, on a fairly regular schedule.

Some fish -- especially pelagics -- hunt at night, and rest during the day. Most reef fish are very busy during the day, so they rest at night. They stop moving about and enter a sleep-like state. While they are resting, they are generally sluggish and not very alert. We try our best not to startle them or disturb their rest during our night dives.

Some fish lie on the bottom to rest, while others hang motionless in the water column. Small fish, in particular, often hide while they are in their somnolent state so that their predators can't find them and eat them. Staying out in the open to rest definitely would give their predators an unfair advantage. In the first photo on this page, a tiny fish called a Pygmy Toby (Canthigaster pygmaea) has snuggled itself amongst corals and sponges to "sleep."

In the second photo, a small fish has chosen to settle into a stand of fire coral to takes its rest. We're not sure what species of fish this is, although the shape suggests that it is some kind of Damselfish.

In addition to hiding, another strategy that many fish use to discourage predation while they rest is to change color. Their color may darken or become mottled during periods of rest, helping them to blend in with their environmental background.

Some species of Parrotfish hide themselves by spinning a slimy cocoon around themselves. The mucous cocoon is secreted from an organ in the head of the Parrotfish. (Sorry, I don't have a photo handy.) It is thought that, in addition to hiding the fish, the cocoon also masks the animals' scent, making it harder for predators to locate them.

Both of the images on this page were captured during night dives in the Red Sea, along the coast of the Sinai Peninsula.

The Leaf Scorpionfish

Meet the Leaf Scorpionfish (Taenianotus triacanthus). This little fishie is one of the smallest members of the Scorpionfish family. This fish family, Scorpaenidae, gets its name from the venomous spines that most of the fishes in the family bear. (Regular readers of The Right Blue will recall our posts about the Turkeyfish/Lionfish -- another member of the same family.)

The Leaf Scorpionfish gets its name from its appearance. When you see one in its natural environment, it really does look like a leaf, rather than a fish -- until you spot its eye! Members of the Scorpaenidae family tend to be "lie-and-wait" predators. They tend to stay still in one spot until their prey happens past, and then they pounce very suddenly. They rely on camouflage so that they can blend into their surroundings, making it easier for them to surprise their prey.

The bodies of Leaf Scorpionfish are laterally very flat, which certainly contributes to their leaf-like appearance. This little fish not only looks very much like a leaf, it also behaves like a leaf! If you stay still and watch one for awhile, you'll see the little guy rock back and forth every once in awhile, just as a leaf or a stray piece of seaweed would do if it had settled on the reef. This, too, seems calculated to trick potential prey.

The Leaf Scorpionfish is a small species -- maximum length is about four inches (10 cm). They come in lots of colors -- yellow, reddish, purple, brown, pale pink, and off-white. They often have blotches, which enhance their camouflage, and they sport little fleshy appendages on their heads and chins that look like little weeds growing on them.

The photos on this page show examples of some of the color variations of the Leaf Scorpionfish. Despite the range of colors, they are all the same species. (Click on the photos to enlarge.)

The first photo on this page shows a purple Leaf Scorpionfish. You can see that this individual has a lot of blotches. If you see a scuzzy-looking Leaf Scorpionfish, he's probably getting ready to molt, which they do periodically. Soon after they molt they look much less blotchy. Sometimes the color looks a bit different after molting, too.

The second photo is a 1:1 macro shot of a Leaf Scorpionfish that we watched over a period of many months. In the second photo, you can see the little fleshy appendages on the fish's chin quite clearly. It's all part of the disguise.

We've noticed that when one of these fish finds a good spot on the reef, they tend to stay put in the same small patch of real estate for a long time. Once one is located, it's a safe bet that a diver will be able to return to the same spot again and again, day after day, month after month, and see the same little fish. Good dive guides know this, and that is why they can reliably lead divers and underwater photographers to a Leaf Fish almost at will.

The final photo on this page shows one more color variety. This yellow Leaf Scorpionfish is perched on a coral head. We have noticed that smaller Leaf Scorpionfish often tend to hide in the coral this way, while the larger ones seem to prefer a spot on a rocky bottom. We don't know why this is so, but we surmise that the little ones may feel safer in the coral, since it affords them some protection. They can hunker down if there's a lot of surge, for instance.

I took all of the photos on this page at Puako, Hawaii, at depths ranging from less than 20 feet (6 m) to about 125 ft (38 m).

Tales of Whales: Close Encounters with Humpbacks in Hawaii

I should mention at the outset of this tale that, since Humpback Whales are a protected species, it is unlawful to pursue or otherwise interfere with them, either from the surface or underwater. People, whether on boats or in the water as swimmers or divers, are forbidden to approach "closer than 100 yards of any humpback whale or closer than 300 yards of a humpback mother and calf," according to the law.

On the other hand, the whales themselves are oblivious to (and excused from) such regulations. If they decide to, they are free to approach us, instead of the other way around. And once in awhile they do just that!

As it happens, our very first underwater whale encounter also was the most dramatic. Or perhaps it seems like that because like so many other 'first time' events in life, it left such a vivid and indelible memory.

Jerry and I were diving at Puako, Hawaii near a certain underwater promontory known as Snapper Point. At the top of Snapper Point, a narrow plateau juts seaward like a coral-covered peninsula. The top of the plateau begins at a depth of about 20 meters (65 ft), then the terrain slopes down steeply to a depth of nearly 40 meters (130 feet), where it levels off, more or less, into a sand flat. It always has been a favorite dive: Swim from shore directly to the base of Snapper Point, have a look around at the sand community for a few minutes, then begin a gradual ascent along the steep and rocky slope to the plateau, finally moving across the coral gardens toward the shallows and shore. It's a classic multi-level dive.

Because Snapper Point is sort of like the last outpost between the shore and the deep blue abyss, we often see big animals there. Sharks, eagle rays, mantas, amberjacks, barracuda, tuna and assorted pelagics cruise past Snapper Point frequently. We also see pods of dolphins in the area from time to time, and sometimes they see us, too, and dive down to look us over. In fact, the possibility of seeing big stuff is a main attraction for diving at Snapper Point.

Then one day at Snapper Point we saw the biggest of the big stuff.

On the day of our first whale encounter, we had completed the deepest part of our dive at Snapper Point, and we were coming slowly up the slope, poking lazily along, looking for shells and little critters on the rocky bank. Just like always.

We were a few meters below the level of the plateau when a shadow passed over us. We both stopped and looked up at the same moment -- just in time to see a full-grown Humpback Whale do a jackknife dive from the surface and glide down toward us. We were stunned.

The whale, which looked to be about the size of a city bus, leveled off just at our depth, at a spot maybe five meters in front of us. It stopped and held its position for a moment, pectoral fins akimbo, and with an eye the size of a basketball, it just looked right at us. I think we actually stopped breathing for a moment, and I'm sure that our eyes, too, were about as big as they could get!

Next the whale drew its pectoral fins in to its sides, banked slightly to its right, and began to glide away. Only when it completed its turn toward the blue did it move its huge tail to propel itself. The last we saw of it was the white undersides of its enormous tail flukes -- easily 10 or 12 feet wide (although we didn't exactly get to measure!) -- beating up and down gently but purposefully as it left us.

That was the end of that dive for us. We could think of nothing but the whale, so we ceased our underwater sightseeing for the day and headed toward the shallows and our exit point.

One of the most striking things about that encounter, beyond the fact that the whale came so close to us in the first place, was noticing how graceful and agile it was. You'd think an animal so large would just lumber about -- a bull in a china shop, as it were. What we saw suggested anything but clumsiness. The whale dived just as deep as it needed to in order to inspect us. Then it paused, motionless, with what any diver would recognize as excellent buoyancy control. And when it left us, it made what can only be described as a precision departure. No thrash, no clunky moves. Clearly it was exquisitely aware of -- and in control of -- its body position, and that of its fins and tail flukes. That is what was so impressive, and what burned into our memory.

While that was our most dramatic whale encounter, it was not the last. On a number of occasions since then, we have seen whales underwater. Most encounters have happened while we were in buoy mode (which I described in the previous whale post), positioned near a dropoff or near the top of Snapper Point, just waiting (and hoping) for the whales to pass by. Very often we would wait like that -- sometimes for up to an hour -- and see nothing but little fishies, or perhaps a manta as a consolation prize. But once or twice in a season a whale or two will swim past us at relatively close range, as if rewarding us for our dedication and patience.

Do they notice us? I have to say, yes, I believe they do. In some instances I have been completely certain that they noticed us. An example that comes to mind right away: Along with our friend Dan, we had spent about forty minutes one day, waiting in buoy mode over a certain dropoff, because we'd seen whales on the surface in that area, just as we were entering the water. It was a cold day, and eventually Jerry signaled that he was going to end his dive and swim to shore because he was too chilled. Dan and I were getting cold, too, but decided to remain at the dropoff awhile longer. Several more minutes went by, and then along came a pair of huge Humpbacks. They swam past, close enough that we felt turbulence. It was really exciting. Spontaneously and in unison, both Dan and I were 'punching the sky' in delight. And believe it or not, one of the whales slowed slightly and looked back at us momentarily, as if to say, "What in the heck is THAT?!"

We have learned something about when to expect a whale encounter, or more correctly, when not to. We have noticed that when we hear the whales vocalizing, we never see them, even when the sounds are so loud that we imagine they must be just feet away. Without exception, every time we have come face to face with a Humpback underwater, it has been during an interval of whale silence. We think, perhaps, that they just don't vocalize much while they are swimming. Of course, neither do we.

About the Photo : I've never been able to photograph a whale underwater. Either I haven't had a camera when the whales appeared, or else I had a camera but it was set up for macro. I chose the photo above from the NOAA Photo Library. According to the notation there, the photographer was Dr. Louis Herman, who has had a long career studying the behavior, sensory processes and cognition of cetaceans. It seems fitting that we use Dr. Herman's photo to illustrate our story: When I was a graduate student at the University of Hawaii (UH), several visits to the Kewalo Basin Marine Mammal Laboratory in Honolulu, which Dr. Herman founded, gave me my first exposure to cetacean behavior. Dr. Herman is now a Professor Emeritus at UH.

Note: This is the third post in a series about the Humpback Whales that winter in Hawaii. In case you have not seen them, you may want to have a look at the two earlier episodes:

• Tales of Whales: Humpbacks in Hawaii - includes a brief video of the whales, plus a link to a live web cam at Puako, where we dive. You may be able to see the whales for yourself if you are lucky!
• Tales of Whales: Vocal Visitations - tells of hearing the whales underwater, and includes a link so that you can listen to the whales' songs and vocalizations, just as we hear them underwater.
  

Tales of Whales: Vocal Visitations

Yesterday we introduced our readers to Hawaii's humpback whales (Megaptera novaeangliae), the huge marine mammals that frequent our waters in large numbers every year during the winter months. At this time of year, the whales' presence dominates in this part of the Pacific Ocean. Not only do we see them daily from the surface as they spout, breach, and slap the surface of the water with their fins and tail flukes, we hear them incessantly beneath the ocean's surface. And sometimes, if we are lucky, we see them underwater as well.

Mostly, we hear the whales. The term whale songs has been used for years to describe the humpbacks' vocalizations. At times they do indeed 'sing', but believe me, a lot of what we hear from the whales is not exactly melodious. They snort, they whine, they trill, they grunt and groan. They make assorted barnyard sounds.

They say "whoop, whoop, whoop" and then purr so loudly that the sounds resonate in a diver's body. When the whales are relatively close by, we can physically feel the sound waves their vocalizations generate, perceiving them as palpable vibrations in our own rib cages, in addition to hearing them.

We think of these events as vocal visitations by the whales. The term 'visitation' may suggest something akin to a spiritual experience in your mind. Without exaggeration, that is what the term is meant to evoke. It's impossible to experience these visitations without having an exquisite sense of awe, in the purest meaning of the word, and without feeling very privileged indeed.

Many, many times during our winter dives at Puako, the whale sounds have been so loud and persistent that they are completely distracting. At their loudest, the sounds are close to overpowering.

At such times there is really nothing to do but to settle on a sand patch somewhere to be still and just listen, because it's impossible to do or think of anything else. If there is nowhere safe or convenient to settle, we take up a posture that we call 'buoy mode,' which Jerry is demonstrating in the photo on this page. Buoy mode entails positioning oneself in the water column, suspended somewhere below the surface, but well above the bottom. The idea is to remain quiet and immobile. In this case we use buoy mode to listen to the whales in a kind of motionless meditation.

Sometimes we hear the calls of an individual whale. More often we are party to what clearly are conversations amongst a number of whales. But, almost without exception, every time we actually have seen whales underwater, the encounter has occurred during a period of silence on the part of the whales. Then out of the blue -- very literally in this case! -- there's a whale (or two or three), right before our eyes.

We'll tell you about some of our face-to-face encounters with humpback whales in Hawaii in our next regular post (after Wordless Wednesday!), but meanwhile we encourage everyone to visit The Whalesong Project to listen to the kinds of whale vocalizations that we hear all winter when we dive at Puako. When you get to the website, click on the phrase "We are bringing Whalesongs to the World" near the top of the page. Let the recording load in your favorite media player, and then sit back, close your eyes, and experience a humpback whale vocal visitation for yourself.

Tales of Whales: Humpbacks in Hawaii

One of the most wonderful -- and wondrous -- things about diving here in Hawaii, is the fact that some 10,000 humpback whales (Megaptera novaeangliae) spend the winter months in our waters. During the winter months, we get to see them frequently on the surface, and once in awhile, underwater as well.

Our blogger friend Sheila put up a humpback whale video on her site yesterday, and it reminded us to share some whale tales with our readers. For openers, here's the video:



(If the video does not play or display properly above, click here to view it on YouTube.)

The humpbacks that come to Hawaii every winter are a part of the North Pacific population that spend their summers in Alaskan waters. They pass the summer feeding, mostly, and then migrate south to warmer waters in winter. Some of these whales winter in the eastern Pacific, near Baja California, while the rest come here to Hawaii. It is here that they mate, and where the mama whales who successfully mated the year before give birth to their calves.

The whales begin arriving for the season in late Fall. We usually spot the first ones some time between Thanksgiving and Christmas. The arrival of the whales is a big deal to those of us who live near the coast or spend time in the water. Neighbors vie to be the first to spot the whales as they arrive, and to spread the word, "They're here! They're here!"

We see them offshore frequently, throughout the winter. We see them spout when they come to the surface to breathe. As mammals the whales are air breathers, and even though they can hold their breath for quite a long time, they must come up to the surface regularly for air.

The humpbacks play near the surface, too. They slap the surface of the ocean with their tail flukes, or with their big, flat pectoral fins. They breach and frolic with one another. Quite often we see the mama whales with their youngsters breaching almost simultaneously -- a real sight to behold!

These are huge creatures, weighing over 40 tons at adulthood. Despite their mass, they are very agile in the water. In the video you'll see one whale manage to leap almost completely out of the water. We call that maneuver a "full pickle" -- a term based on an apt description we once heard: that the humpback whale sort of resembles a huge dill pickle, with ceiling fan blades for pectoral fins. I can't recall exactly where we heard that, but the image stuck, and we began referring to a full breach as a "full pickle."

Here's a link to a live web cam at Puako, where we dive most often, so you can see what we see from the shore. If you're lucky, you just may see some whales. (You can also see what our weather and ocean surface conditions are like, in real time!)

In the next post we'll tell you about some encounters we've had with humpback whales. Meanwhile, you can find out more about these incredible creatures at these recommended websites:

• Hawaiian Islands Humpback Whale National Marine Sanctuary - NOAA
• Getting to Know the Humpback Whale - The Dolphin Institute

Next: Encountering humpback whales underwater.

A little fish with a big job

This is an enlarged photo of a little bitty fish --but he's a little fish with a big, important job. Meet the Hawaiian Cleaner Wrasse (Labroides phthirophagus).

These little fellows -- only two to four inches long as adults -- make their living by keeping other fish clean. They are an important part of the reef community.

The little cleaner wrasse stakes out a spot on the reef, usually near a prominent coral head. He hovers above the coral in a head-up posture and wiggles. That's the cleaner wrasse equivalent of turning on a neon sign that says "OPEN."

Other fish come as clients to the cleaning station to be rid of bits of old scales, dead skin, and small parasites that they may have acquired. The client fish swims up to the cleaner wrasse and stops. The cleaner wrasse approaches and gives his client a once over, looking all for extraneous bits, which he then pecks off. This service can take anywhere from a moment, to several minutes, depending on how big the client is -- and how scruffy!

Here's a photo of a Hawaiian Cleaner Wrasse servicing a Spotted Puffer (Arothron meleagris) at Puako. [And yes -- in case you were wondering -- the Spotted Puffer is a first cousin to the Stripebelly Puffer that we showed you a number of weeks ago. They belong to the same genus.]

These cleaning stations serve pelagic (open ocean) fish as well as reef fish. It's not unusual to see animals like sharks, manta rays, and large jacks waiting their turn at busy cleaning stations.

Once a cleaning station is established, it will exist for a long time -- even for years -- in the same spot. Client fish learn where it is, and return to it again and again. The busier cleaning stations may have several cleaners at work -- much like a barber shop with multiple chairs.

Some fish that don't clean other fish full time, do become cleaners from time to time. An example that comes quickly to mind are the several species of fish that clean turtles here in Hawaii. It happens that turtles' carapaces sometimes get covered with a film of algae. Certain fish that are primarily algae-eaters will clean the turtles' shells -- not because they are trying to clean them but because they like to eat the algae, regardless of whether it's growing on a rock, on a coral head, or on the back of a turtle.

Several species of shrimp also make their living cleaning other animals on the reef, and they act as dental hygienists as well. It's not at all uncommon to see a toothsome moray eel -- jaws agape -- with a little cleaner shrimp busily pecking about inside the eel's mouth. (Moray eels don't floss!)

We've played with both the cleaner wrasse and the shrimp to see if we could get them to work on us. The wrasses rarely seemed very interested in us, save for occasionally snipping at Jerry's whiskers. The cleaner shrimp are another story entirely. They'll readily crawl around on our hands, pecking at our cuticles, for example. And by the way, that REALLY tickles!

The cleaner wrasse in the photos on this page is endemic to the Hawaiian Islands. That is, it is native to our waters and exists naturally only here. But, it has close relatives in other parts of the world that look very similar, and which serve the same function in their own locales.

You don't know jacks...

...but we do!

We know jacks (Family: Carangidae), and they are among our favorite kinds of fish. The family has many species, and everywhere in the world that we have dived we have encountered several species of jacks.

One species we've seen in numerous locations is the Bigeye Trevally (Caranx sexfasciatus). In fact we've seen these guys everywhere from the Red Sea, through the Indo-Pacific region, to Hawaii.

Bigeye Trevally - a.k.a. Bigeye Jacks - tend to gather in fairly large schools during the daylight hours. Usually they'll hang out with their gang along a dropoff or reef slope all day long.

Around dusk, they fan out into the open ocean to hunt all night as individuals. In the morning, they find their 'schoolmates' again and reconvene to spend the day near the same dropoff. Once they form up, they often swirl around in a dense pack -- a way for them to keep together and stay more or less in one place. It really is a sight to see.

Jerry likes to play with these jacks. In fact, what he likes to do is herd them. That's right, I said herd them! He discovered that he can approach a loose aggregation of these fish while they're still a bit offshore in the bottomless blue, and coax them to go more or less where he wants them to go by swimming alongside them, much like a cowboy would ride alongside a herd of cattle.

We had been diving along this particular dropoff very early in the morning for several days in a row. Each morning we had seen the jacks in more or less the same area. I was able to take quite a few shots of this very photogenic school of Bigeye Trevally, and while I was busy taking photos, Jerry was perfecting his herding skills.

I watched him for a little while and decided it would be fun to shoot a series of photos of Jerry-the-Jacks-Wrangler in action, demonstrating his fish herding skills. As you can see in the first two photos on this page, Jerry was able to herd the jacks from offshore to the edge of the reef and nudge them into a denser aggregation. These fish are ever-moving, of course, and eventually they would begin to swirl. When that happened, we'd swim out, away from the dropoff, and then look back just to watch them swirling. From that perspective it was quite a hypnotic sight.

On the morning this series of photos was taken, I had suggested ahead of time that after the jacks schooled and began swirling, Jerry try to get inside the swirl. I thought it would make an interesting photo.

Ever the cooperative model for my underwater photos, Jerry agreed to try to get inside the cyclone of Bigeye Trevally.

The fish kept swirling and swirling, and I kept on snapping the shutter, even though it was difficult to keep things in focus with all that motion. What an action sequence!

For his part, Jerry found that he could not remain stationary once he was inside the swirl. In fact, we eventually had to stop because Jerry was becoming quite dizzy!

I think the caption for this final photo in the sequence should be, "Can I stop now? Please???"

If these schooling jacks look somewhat familiar, it might be because they are also featured in the photo in the header of The Right Blue. The images were shot at Sipadan, an oceanic island in the Celebes Sea, off the coast of Borneo.

Night shift on the reef

There are nocturnal animals in the sea, just as there are on land. Many marine animals hide all day and only come out at night to hunt, feed, or mate.

The colonial anemone pictured here (Nemanthus annamensis) is one such nocturnal marine animal -- part of the underwater 'night shift' that begins shortly after sunset and lasts until dawn. The only way to see these nocturnal marine creatures is to dive at night.

The anemones in these colonies open as soon as it gets dark. During the night they look like pretty flowers, with their tentacles extended to feed. When morning comes they fold their tentacles inward and each one of the 'flowers' turns into a tightly shut fist. While they are closed during the day they look like nondescript lumps, their nighttime beauty obscured.

The photo was taken during a night dive in the Red Sea, near Sharm el Sheikh, Egypt. If you click on the photo it will enlarge.

Picture this! -- Photographing the photographer

Recently someone asked us, "How come there are hardly any pictures of Bobbie on The Right Blue?" The answer to that question is that I've always been the one behind the camera instead of in front of it. As a result, we have very few underwater photos of me.

Ever since we began The Right Blue, Jerry has been going through the thousands of slides we had stashed away, methodically looking for the ones that have a story. Several days ago he came across the one at right. Fortunately it was filed away along with the one below. Jerry scanned them both and passed the images to me to write about.

The first photo was taken by a dive guide and given to me as a souvenir of a trip we made to the Turks and Caicos islands. That's me, stalking my prey -- sneaking up on an interesting photo subject.

The second image is the photo I snapped a few moments later. I had followed this pair of critters around the sand flat for nearly ten minutes before they lined up just right for me to take the shot. I've mentioned in earlier posts that I really love to take pictures of critters' faces and especially their eyes. My next favorite theme after faces and eyes is behavior.

The dark colored fish in the photo is a Bar Jack (Caranx ruber). This fish makes its living as an opportunistic feeder, so it is swimming along a little above and behind a Southern Stingray (Dasyatis americana) hoping to snag a free lunch.

The stingray rummages in the sand looking for little creatures to eat -- worms, small clams, tiny crabs, and such. To locate its prey, it fans away the top layer the sand by fluttering its wingtips.

The crafty Bar Jack follows closely, letting the stingray do the excavating. If the stingray uncovers something that looks tasty to the Bar Jack, the jack will snatch it in a lightning strike, then resume its position keeping watch over the stingray's shoulder, as it were.

We've seen Bar Jacks throughout the Caribbean. In addition to pairing with hunting stingrays, we've also seen them following goatfish -- another species that digs around in the sand and rubble for food.

By the way, the Bar Jack doesn't always look so dark. When it's not feeding, it is a handsome silvery blue color, with a black bar running along its back from its dorsal fin down to the lower lobe of its tail fin like a racing stripe.

Myrtle's special spot on the Puako reef

Puako, Hawaii is blessed with a spectacular fringe reef that runs parallel to the shoreline, but if you are beginning a dive from shore, you have to swim a bit to get to the reef. I mentioned in an earlier post that the inshore water is shallow, due to a lava shelf that extends seaward from the shoreline. That shelf ends at a precipitous dropoff. There the water depth abruptly changes from one or two meters, to about eight to ten meters. It takes most people a solid five to ten minutes of swimming to get to the dropoff, but it's worth the effort.

The underwater terrain along the seaward face of the dropoff is dramatic. There are cavelets and tunnels and arches formed by the ancient lava flow, all of which are now covered with coral and other marine growth, and inhabited by a multitude of fish and little creatures.

Beginning at the base of the dropoff and extending seaward is a vast coral garden, composed mostly of a species of finger coral (Porites compressa), with other hard corals in patches here and there. These acres and acres of coral form the main fringe reef that parallels the entire coast of Puako and beyond.

This area is densely populated with abundant marine life of all kinds: Virtually every type of fish or reef creature known to live in Hawaiian waters can be found somewhere along Puako's reef.

The green sea turtles in Puako spend a good bit of their time feeding in the shallows, or basking on the edge of the shore. They also spend a part of each day on the reef. The terrain on the reef is nearly level in some areas, gently sloping in others. There are holes and ledges here and there, and some of those are turtle hideouts.

The turtles near the shoreline favor a particular area for grazing and sunning themselves. Once you are able to recognize an individual turtle you will be able to reliably find that turtle in the same area, day after day. This certainly was the case for the turtle we named Myrtle.

From the time we first came to know her, we would occasionally cross paths with Myrtle near the dropoff. Usually we would pass her swimming in the opposite direction -- either she'd be heading in to shore when we were headed out for a dive, or she'd be approaching the dropoff just as we were ascending at the end of our dive. We always wondered where she went on the reef, but it was a long time before we encountered her beyond the dropoff.

Finally we spotted her one day, swimming over the coral garden. As soon as we were sure it really was Myrtle, we signaled to each other to follow her. We were so curious to see where she would go.

She seemed very unconcerned to have us swimming alongside her. She stayed her course and neither sped up nor slowed her pace. After a few minutes we approached a rather large hump in the coral. Myrtle ceased paddling with her flippers. She glided toward the coral formation and plopped down near its base. She landed a bit clumsily, then turned around and snuggled her turtle butt into a depression in the coral. There she rested.

We watched her there for a few minutes. She looked a bit like an old lady sitting on her porch, watching the world go by. She looked our way a few times, but seemed quite settled, so we swam off.

About an hour later as we were headed back across the reef toward the dropoff for our ascent, we chose our route to pass by the same lumpy coral formation. We checked the hole where we last saw Myrtle. Myrtle was gone.

But then, guess who we saw as we waded ashore: Myrtle, of course, back in her favorite cove, grazing on limu as usual. And now that we knew the location of Myrtle's secret spot on the reef, we knew just where to look for her when she wasn't in the shallows or on the beach.

Meet Myrtle the turtle

As I explained earlier, many green sea turtles live along the shoreline at Puako, Hawaii. They cruise around the reef, graze on algae and seaweed in the shallows, and sunbathe on the rocks and beaches there. We'd like to introduce you to one of those turtles.

This is Myrtle, a Hawaiian green sea turtle (Chelonia mydas). Over a period of several years, we got to know Myrtle quite well. Because we got to know Myrtle, we learned a lot about green sea turtles and how they live.

Myrtle's base of operations in Puako happened to be the particular little cove where we most often enter the water to begin our shore dives. While quite a few turtles hang out in that area, we noticed that one particular turtle had a small 'ding' right in the center of her carapace. That little blemish in her shell set her apart from the others and made her easy to identify. We named her Myrtle -- not the most original name for a turtle, I know, but it suited her. (Take a look at that face in the photo and tell me she doesn't look like a Myrtle!)

At the time we first encountered Myrtle, Jerry and I were living in Puako, right across the street from the little cove where this turtle lived. Our good friend Dan lived just up the road. During the time that we all lived there, Dan and Jerry and I visited the cove on a daily basis, whether we were diving or not. It was during this period that this spot became our favorite, and that we got to know Myrtle.

Once we learned to recognize Myrtle, we noticed that she was there almost all the time. So, one of the first things we learned from Myrtle is that green sea turtles are creatures of habit.

Sometimes we'd see her basking on the beach, 'working on her tan.' Most often we'd see Myrtle in the water close to shore, munching away on the limu (seaweed) that covers the rocks there in the shallows, just as she's doing in the photo at right. Occasionally we'd cross paths with her while diving out on the reef beyond the dropoff. More on that later...

Most of the sea turtles around Puako are quite laid back, especially when they're basking on the rocks or the beach. By this I mean that they are not very skittish in the presence of people -- almost as if they know they are protected by law, and that no human will harm them. (Either that, or the warm sun just makes them drowsy!)

The sea turtles in Puako can be a little touchy about having their space invaded when they are feeding, however. If waders approach them, they'll often pointedly shove off from the bottom and swim at least a few meters away. We'd see Myrtle do that, too, but then we noticed something interesting.

As I mentioned, we had almost daily encounters with Myrtle for years. We began to notice that if we waded past Myrtle while wearing our wetsuits and dive boots, she never spooked. Perhaps she grew accustomed to seeing us -- or rather our neoprene-clad legs and feet! -- and understood that the humans attached to those legs and feet were not going to harass her. That thought was reinforced by the fact that if we waded into the water bare-legged, bam! Myrtle would take off.

There is a sound reason why sea turtles tend to stay clear of anything unfamiliar, including people, while they are underwater. Sea turtles can stay underwater for a considerable length of time, but they are air breath