The chain catshark, also known as the chain dogfish (confusing, I know) is a small, uniquely patterned shark with a special power: it has fluorescence!
Mikhail Matz, a marine biology professor at the University of Florida first observed this unique property in 2005, catching it on film. No one is sure what the purpose of this unique characteristic is, and more research needs to be done on it.
They are found swimming on the bottom of outer continental shelves and upper slopes, usually around 58 to 359 meters (190-1,178 ft). It can also be seen at shallower depths. These animals mostly spend their time resting in cozy structures, probably camouflaging with its surroundings. Predators include larger fish and sharks.
Sometimes kept in aquariums, they rarely swim about. However, when they do move around, they're looking for a quick meal. These small critters are known to feast on teleost fish, squid, polychaetes and crustaceans.
Females tend to be bigger (0.52 m or 1.7 ft) than males (0.50 m or 1.64 ft). Mating has been observed in these animals, showing that males bite onto pectoral fins for a better grip and mating occurs repeatedly. The female can store sperm and lay eggs (always in a pair) from different sperm pockets. The two eggs can have a birth interval of a few minute to almost a week!
Egg cases are a dark brown/amber color with white bands and two coiled tendrils, allowing them to snag onto rocks or other structures. Embryos take 8-12 months, depending on temperature in the water. Eggs are laid in their blastodisc form.
The chain dogfish is currently listed as a species of "Least Concern" by the IUCN.