Hawaii's Gold Lace Nudibranch

by B. N. Sullivan

Continuing our series on nudibranchs (see previous post on Exotic Underwater Nudies...), today we present the Gold Lace nudibranch (Halgerda terramtuentis). This pretty mollusc is endemic to Hawaii -- that is, it is only found in the waters around the Hawaiian Islands.

It has a pale yellow translucent body overlaid with a lacy network of irregular yellow-orange lines, and a solid yellow-orange line bordering the entire edge of its mantle. It also has little bumps, called tubercles, all over its body, which are a lighter color -- almost white on some individuals.

As if its body were not pretty enough, take a look at those accessories: Its tree-like gills and its rhinophores -- those sensory organs protruding from its head -- are white with black speckles.

While these little critters are found only in Hawaii, they are fairly common here. Both of the individuals pictured on this page were photographed at Puako, Hawaii, where the species is plentiful along the area known as the first dropoff, where they live in small cavelets and in rocky areas. We see them most often at relatively shallow depths -- less than 10 meters/30 ft.

I took both of the photos on this page inside a small cavelet. The individual in the photo above was crawling along the ceiling of the cave, and got dislodged by our exhaled bubbles. On impulse, I snapped a shot of it as it floated downward through the water, and amazingly, it turned out to be a pretty good 'species ID' shot! The second photo is more naturalistic. Because the nudie is crawling across a red encrusting sponge, you can get an idea of its 'see-through' translucence.

Gold Lace nudies are small -- usually between one and two inches (up to 5 cm) in length. They are carnivorous, but they don't "bite." They feed on sponges and other soft organisms.

This nudibranch was officially identified relatively recently - in 1982 - by Hans Bertsch and Scott Johnson of the University of Hawaii. (Many nudibranch species have been officially recorded in the scientific literature since the 1800s.)

By tradition, the scientists who officially discover a species get to name it. This creature's species name has an interesting story. Terramtuentis means "looking at the earth with care." The name was given in honor of a group of Earthwatch volunteers who assisted Bertsch and Johnson with their research.