General: Chimaeras

2/17/2016

God, where do we start with these odd-looking animals? They have… well, it’s like a club... on their nose. Their eyes are a pretty shade of green (usually) and are pretty large and high on their weird-looking heads. And then they just have one gill opening, and these large pectoral fins and widely spaced dorsal fins… they just don’t make sense! Not to mention they have a spine on the first dorsal fin to defend themselves.

Like their sharky “counterparts,” they have claspers- expect these are shaped like spoons and are pretty weird looking. Yeah, think of chimera claspers next time you eat with a spoon. Appetizing, no?

To make things even freakier, they have a thumb-shaped clasper on their head, which basically makes it so females can’t move away during copulation. Now look at your thumb, and look back at the screen. Back down at your thumb… chimera clasper.

You’re welcome.

They aren’t true sharks, even though nicknamed "ghost sharks." Chimaeras (in the Chimaeriformes order) are also known as “ratfish,” “rabbit fish,” “elephant fish” or “spook fish.” And sorry, but we’re not talking about the crappy movie.

We can find these spooky animals in a lot of places, such as off the coast of Canada and even in the the southwestern temperate coasts of south Australia and New Zealand. They can be seen perusing the continental shelves of cooler waters, usually in the deeper waters (around 220 m/660 ft). It has been noted to migrate to shallow estuaries or bays in the spring to get it on (aka mate, mates).

It’s not hard to distinguish between the ghost shark and true sharks. They are like smooth like aluminum (unlike true sharks) and color differs between species (though most are dark-colored).

Unlike many true sharks, they have tooth plates instead of individual teeth. The upper jaw plates are sharp, while lower jaw plates are flat and used to crush the prey held in place by the upper jaw. (Melissa's random thought #22429: I feel like I should have this sort of tooth arrangement, so I can keep my chocolate chip cookies from escaping.)

Another key difference in the dentition of chimeras and sharks? Their teeth don’t fall out! Instead, they just continue to grow. Speaking of growing, they don’t get pretty big (with max reported size being 1.25 m/4 ft), lasting to a ripe 15 years. They get tired of your shenanigans real quick, apparently. “Get off my continental shelf, you scallywags!”

Now, remember that club-thing on their face? No, it’s not a pimple. It actually has a purpose. It’s actually covered in pores, which sense movement and electrical field, allowing for these animals to find prey (i.e. shellfish and molluscs).

They are oviparous, with eggs (normally two) deposited in muddy/sandy shallow waters during the spring. They are golden in color, but eventually turn brown/black before releasing the baby into the big, wide oceanic world. As they mature, they will migrate from the safety of the shallows into the deeper waters.

These "sharks" are caught along southern Australia (AU) and New Zealand (NZ) commercially, often used in "fish and chips" (eek!). They are also highly consumed by the Ngai Tahu Maori tribe. In fact, about 80% of NZ catch is that for this tribe! Besides the spine on the dorsal fin, they pose little to no threat to humans. Their IUCN status varies between species.

what did you think of this animal?

glossary

Claspers: Sexual reproduction organs found on male elasmobranchs and chimaeras.
Continental shelf: Extends from a continent underwater, resulting in a shallow-water area.
Copulation: Mate (i.e. have sex).
Dorsal fin: Fin located on the back.
IUCN: International Union for Conservation of Nature.
Molluscs: The largest marine phylum; invertebrate animals, many of which have shells.
Oviparity/oviparous: Where adult Chondrichthyans lay eggcases (also known as ‘mermaid’s purses) and the baby develops inside the egg before hatching.
Pectoral fins: Fins located behind the gills on either side.
Pup: Give birth to baby sharks (pups).
Pups: Baby sharks.
Shellfish: Animals like oysters, clams, shrimp, scallops, mussels, etc.