This Deep-Sea Crustacean Is The Size Of A Loaf Of Bread. It Looks Like A Giant Prawn, Begging The Question: Would It Taste Like One?

Though ghostly in appearance and rarely seen given A. gigantea’s preferred depth of 3,890 to 8,931 meters (12,762 to 29,302 feet), these amphipods may actually be one of the most ubiquitous animals on the planet. Just last year a paper published in Royal Society Open Science revealed this supergiant species may inhabit over half of the world’s oceans.

They analyzed almost 200 records of A. gigantea from 75 locations on the seabed and the results suggested they’re thriving across 59 percent of Earth’s oceans, albeit at a vast and extreme depth.

When mettle meets metal

It’s worth noting that while A. gigantea lives pretty deep, its relatives go much deeper. Hirondellea gigas was found at the bottom of the Challenger deep, an impressive 10,000 meters (33,000 feet) below the sea. It's a depth at which most crustaceans would risk getting dissolved due to a combination of high pressure, low temperature, and acidity.

That's because crustaceans mostly have a hard exoskeleton made up of chitin and calcium carbonate, but H. gigas evolved to become the first known organism to create an alternative suit of armor made of *checks notes* aluminum.

A particularly weird discovery because aluminum isn’t readily available in the open ocean. However, go deep enough and you find loads of it in ocean sediment.

Seems fishy

Despite being so widespread there’s still much we don’t know about how this amphipod’s unique physiology enables it to thrive at such depths. However, a 2022 study in the Journal Of Marine Science And Engineering took a closer look at its composition and yielded a concerning result for its palatability.

It tested specimens of A. gigantea, H. gigas, and the shallow-water shrimp Penaeus vannamei to establish concentrations of trimethylamine N-oxide (TMAO) and trimethylamine (TMA) – two compounds known to play a role in how animals regulate osmotic pressure. 

It found A. gigantea had the highest average TMAO concentration of all three, with its muscle containing 11 times the concentration of the shrimp’s (and that number goes even higher if you’re someone who likes to eat the head).

After death, TMAO converts to TMA, which is the volatile compound responsible for the pungent odor of rotten fish. Having so much TMAO in its tissues could mean that A. gigantea would produce even more TMA after death, stinking to high heaven and likely making it a tough sale at the fish market.

Carcinogenic crustaceans? 

Another catch for anyone hoping to enjoy a deep-sea amphipod lobster roll is that apparently living in the deep sea isn’t enough to protect you from contamination. 

A 2022 paper published in Biological Trace Element Research found that these hadal amphipods contained unusually high concentrations of metal contaminants including, including cadmium, which is a known carcinogen for humans.

While all the seafood we eat is vulnerable to this kind of contamination, there seems to be a bottom-up effect whereby the deep-sea varieties accumulate more than those caught nearer to the surface. It just goes to show how far-reaching pollution events can be, and for this writer puts the final nail in the coffin of any plans to host a supergiant amphipod cookout.

If it’s a novel alternative to shrimp you’re after, you might be better off sampling the delights offered by invasivore diets that could help us eat our way out of some ecological disasters we may have caused. 

Probably for the best not to make any enemies in the deep sea, anyway. Who knows what they’re plotting down there.