Our Chimaera is a little different from the old Greek one. It has the front half of a short, chunky fish and the back end of a long, thin fish. CRAZY!
|Image: Dr. John Butler, NOAA NMFS SWFSC|
There are about 50 species of Chimaera in the world, reaching at most a metre or two (3 or 6 feet) long. The majority of them live in deep, dark waters...
|Image: Claf Hong|
But giant eyes aren't enough, so Chimaeras also have a very visible lateral line running down their body and all over their face. Most fish have a lateral line for detecting pressure and movement in the water, but those of deep sea fish are particularly sensitive and evident. In Chimaeras it looks almost like a kind of face tattoo!
With their large eyes and whip-like tail, Chimaeras look quite a lot like Grenadiers, also known as Rattails. However, Grenadiers are bony fish while Chimaeras are members of the class Chondrichthyes, which is the one with sharks, skates and rays. The name Chondrichthyes means "cartilage fish", since they all have skeletons made of cartilage instead of bone.
It also means that Chimaeras get to make use of another organ of shark-kind known as the ampullae of Lorenzini, which can sense the electromagnetic fields produced by living things. These detectors are situated right on the snout, just above the mouth...
|Image: SERPENT Media Archive Project|
Food consists of molluscs and crustaceans plucked from the sea floor. Chimaeras have their teeth fused into tooth-plates which work like a beak to crush through tough shells. Molluscs and crustaceans aren't the kind of creatures who can swiftly make their escape, which is good because Chimaeras would have a tough time keeping up...
Video: NOAA Okeanos Explorer Program, INDEX-SATAL 2010
Sharks swim using mighty sweeps of their powerful tail and sinuous movements of the body. Chimaeras have a lot of tail, but there's barely any fin on it to push them through the water. Instead, they use their unusually large pectoral fins. However, they have nothing like the mesmeric power of rays and skates, and their flapping results in a rather poor performance. Chimaeras do much better when they don't have to move around too much. The deep sea sounds more and more like an office job...
With this lack of speed and finesse on the move, many Chimaeras have found another way to protect themselves from attack. In front of their dorsal fin is a spike with a venom gland at its base. They sting! The venom is fairly mild though it still hurts. And I imagine it's a lot worse if you get it on the inside of your mouth. If you want to eat something whole while it's still alive, it's important to choose wisely.
|Image: Florian Graner, Sealife Productions|
Apparently these extra organs are used to hold onto the female in some way during mating. It wouldn't surprise me if it makes the whole process easier and means they don't have to move around so much when they're doing it, but I still think they should wear a hat.
|Image: North Atlantic Stepping Stones Science Party, IFE, URI-IAO; NOAA/OAR/OER|
Speaking of extinction, it's interesting to note that there are two kinds of cartilaginous fish in the world: Chimaeras and all the others.
Chimeras on the left, three living groups of sharks and rays on the right. Everything in between is extinct.
And perhaps, with the rise of these new sharks, they were banished to the cold, perpetual wet winter of the deep, clinging to the dark places so ominous to the upsiders. And there, surrounded by the gloom of light in its silent death-throes, they could acquire a sexual organ on their forehead in peace.