With a dorsal fin that resembles a feathered headdress, a transparent body, and a frilly, external stomach that dangles from its neck like a strand of Christmas lights, this fantastical fish looks more like a Star Wars creation than a piece of pelagic plankton. Scientists have documented similar animals only a handful of times, but they now recognize this bizarre member of the ocean’s planktonic soup to be the highly specialized larval form of a cusk-eel, a group of fishes that—despite their common name—are not actually eels. Most cusk-eels are deep-sea dwellers, but they lay eggs that float up to the surface to hatch. The larvae spend their early lives at shallow depths—eventually making their way back down to the bottom, assuming they can avoid being eaten before they have a chance to mature. The trailing external gut on this larval cusk-eel (Lamprogrammus sp.)—which measured approximately 4 cm (1.6 in)— likely enables the animal to absorb dissolved nutrients directly from the surrounding water, helping the creature develop more quickly. Its frilly stomach protrusions may also deter would-be predators, given their resemblance to the stinging cells of a siphonophore colony (picture the Portuguese man o’ war). Biologist Jeffrey Milisen captured this photograph during a night dive off the coast of Kona, Hawaii, becoming the first photographer to ever document this larval cusk-eel alive.

Kailua-Kona, Hawaii

Jeff Milisen

Jeff Milisen is an underwater photojournalist and marine biologist with a penchant for exotic and remote environments. He spent two seasons working with NOAA’s Marine Debris Project picking up derelict fishing gear from the Northwestern Hawaiian Islands. His work is frequently seen in popular publications, and he has been awarded honors in numerous international competitions including the Ocean Art photo contest, Our World Underwater, Beneath the Sea and most recently, Nature’s Best Ocean Views photo contest sponsored by the Smithsonian Institute.

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