Odontodactylus scyllarus – Of smashers, enamel, and relationships

It took me some month to finally come up with a picmybug-worthy story about the Peacock mantis shrimp. It is one of those marine animals which are well-known for certain properties, but on picmybug I am looking for the lesser known details.

All you need to know about O. scyllarus can be found in a brilliant comic, which I urge you to read now! Theoatmeal.com is worth more than one visit, and describes mantis shrimp in an unforgettable way.

The short summary: Mantis shrimp have one of the most complex eyes of all animals, which enable them to see all kinds of colors, much much more than we do. They have powerful arms, and can strike faster than anyone else in the world, as fast as a bullet. So-well-armed, mantis shrimp are more than capable to hunt other crustaceans, molluscs, and fish. Large mantis shrimp are able to break (aquarium) glass, so better think twice whether you want one in your aquarium!

The so-called predatory appendages are either formed like spears, resembling those of a praying mantis, or they look like clubs, allowing e.g O. scyllarus to smash predators, opponents, and food. I wasn’t able to find out how the ratio of smashers and spearers within all mantis shrimp is, but it seems most families of the Stomatopoda are spearers.

The clubs are partially made of calcium apatite, the same material that our teeth (the enamel) are made of. Isn’t it wonderful how we have something in common with a creature that could easily be an alien? It hit me like a mantis shrimp when I looked up the etymology of the name: Odontodactylus scyllarus means something like tooth-finger hermit crab! Tooth finger!

You often see mantis shrimp drawn as boxers with gloves. That is somewhat misleading. The joint of that appendage is held up high, with the club pointing downwards. It is rather a leg than an arm. The punch looks to me much more like a front kick, where the knee is lifted and the foot kicks forwards. Smashers have a thickened heel and flex the foot in an extreme way so to say, while spearers point the foot like you would do in a proper front kick.

O. scyllarus is one of the approximately ten thousand species of living beings described by Carl Linnaeus in the 10th edition of his famous Systema Naturae in 1758. Males are greenish, females more reddish, lobster-shaped crustaceans. They reach approximately 15 to 20cm body length.

The systematics of crustaceans wasn’t too clear to me, so I tried to learn it.

Three of the major subphylums in the phylum Arthropoda are: Chelicerata, with approximately 77.000 species of arachnids; Hexapoda with one million known species of insects, and Crustacea with 67.000 species of crustaceans. It is believed that we have approximately five million species of invertebrates to describe yet.

There are several classes within the subphylum Crustacea, Hexapoda, insects, might be one of them according to recent works. That would make insects kind of land-crustaceans.

All the famous lobsters, shrimps and crabs belong in the class Malacostraca. Even Isopoda, where woodlice belong to, are in that class.

40.000 of the 67.000 known species of crustaceans further belong in the subclass Eumalacostraca. And here waits our story! Woodlouse, orangotang crab, lobster, banded coral shrimp, they’re all Eumalacostraca. Mantis shrimp however have their own subclass, called Hoplocarida. Here they have their own order Stomatopoda.

Did you know there’s almost 500 species of mantis shrimp? See some here in Roy’s list! There are entomologist, or carcinologist, saying they should be placed in Eumalacostraca, but currently a woodlouse is closer related to a cleaner shrimp than the mantis shrimp is. Mantis shrimp are rather distant relatives to shrimp! The separation is due to their special shaped eyes, antennas and the predatory limbs. That’s what you get when you’re special!

Ray Manning, an American carcinologist, has done some of the most important work regarding Stromatopods. Read his amazing story here!