Whitespot ghost shark

1/28/2019

Photo by Ross Robertson

While there aren’t a lot of chimaeras that have been described, it doesn’t mean they deserve the spotlight any less than their relatives, the sharks, skates, and rays. Today at TFUI, we’ll talk about the whitespot ghost shark (Hydrolagus alphus) which was first described in 2006 by four researchers. The common name is actually a nod to the species name, alphus, which is Latin and refers to the spot on the skin of this chimaera.

The whitespot chimaera is only known from four specimens in which researchers Kimberly Quaranta, Dominique Didier, Douglas Long, and David Ebert described. Two of these specimens were caught, while the other two were observed by the scientists. These particular chimaeras were discovered using submersibles—that’s right, SUBS!!
According to the IUCN, the two chimaeras that were caught were an immature female and mature male. The female body length (BL) measured at 24.4 centimeters (9.6 in) and had a total length (TL) of 48 cm (19 in). The male had a BL of 24.9 cm (9.8 in) and a TL of 41.9 cm (16.5 in). Both were brown in and had a single white spot above their pectoral fins, which have a twinge of blue to them. #Finfact: Their first dorsal fin has a long spine in front of it! All of the fins this chimaera has are darker in the middle of the fin and gradually get lighter at the edges, with the skin behind the pectoral fin and second dorsal fin this chimaera has also being lighter in color. Like other chimaeras, they have smooth skin, and they have large, green eyes.

This chimaera is a “benthopelagic” species, meaning you see the whitespot ghost shark in waters close to the sea floor. And by close, we mean CLOSE—they don’t stray further than 3 meters (9.8 ft) from it! They call the depths of about 630–907 m (2,067–2,976 ft) home, loving the steep slopes and boulders on the continental slopes in this area. It loves rocks—according to the IUCN, it frequents "areas of high rocky relief containing volcanic boulders, cobbles, and pebbles, interspersed with patches of sand and silt." If this environmental description sounds familiar, it’s because the Galápagos ghostshark (Hydrolagus mccoskeri) is found in similar habitats, too!
Like other chimaeras, the whitespot chimaera has a carnivorous diet. It munches on worms, shrimp, crabs, and mollusks that live in the cold benthic zone.

You can find these ghost sharks in the southeast Pacific Ocean (i.e. around the waters of the Galapagos Islands). It is possible they are endemic to these islands, but that has yet to be confirmed by researchers. Thankfully, if it is, their range is protected since it is a part of the Galápagos Marine Reserve. It is listed as Data Deficient (DD) by the IUCN.

WHAT DID YOU LEARN ABOUT THIS ANIMAL?

GLOSSARY

Continental shelf: Extends from a continent underwater, resulting in a shallow-water area.
Continental slope: Steep slope descending from continental shelf to the continental rise; typically about 20 km (12.4 miles) wide, consisting of mud and silt.
IUCN: International Union for Conservation of Nature.