Featured Elasmobranch – Pacific Starry Skate

by jkemper ~ May 3rd, 2009. Filed under: Featured Elasmobranch.

May 2009

raja_stellulata_aquarium_pacific_11-08

Pacific Starry Skate

Raja stellulata (Jordan & Gilbert, 1880)

FAMILY RAJIDAE (Hardnose Skates)

Identification: Known as the spiniest of eastern North Pacific hardnosed skates, the Pacific starry skate is covered with prickly spines and abrasive dermal denticles. Its dorsal surface has rows of thorns along its mid-back, groups of orbital thorns, up to six large thorns on its shoulder girdle, and a cluster of thorns along the edge of the pectoral fins or “wings”.  The number of these thorns increases with the size, and therefore the age, of the individual. In contrast, the belly is smooth and whitish, but with dark margins. The nose is very short, and two eyes spots are often visible above the pectoral wings. Its dorsal surface is brown to gray brown, providing effective camouflage on the seafloor however these colors fade upon death.

Size: Starry skates reach a reported maximum total length of 76 cm.

Distribution: Raja stellulata is commonly found from Oregon to Baja California at a depth range of 18-730m.

Habitat: Once commonly referred to as the rock skate, this species is known to live and hunt on rocky habitats.

Biology: Like the other skates, the starry skate is oviparous and lays its egg-cases (also called “mermaid’s purses”) on the seafloor.  Little is known about its reproductive biology, but males mature at about 67 cm and females at about 68 cm. Current investigations about their feeding habits confirm that the Pacific starry skate is a predator on species inhabiting rocky reefs, and may be at the top of the demersal food web along the California coast. It is known to eat rockfishes, poachers, and cephalopods. It also commonly feeds on shrimps and crabs.

General interest: These are harmless skates except for the numerous thorns that may inflict puncture wounds much like one might receive from handling a thorn bush. It is one of only a few skate species in the eastern North Pacific that does not appear to inhabit sandy bottoms, which explains why its diet shows such striking differences with the other local Rajids. With its limited distribution and its position as a top predator, this species is an apex predator in the nearshore food web along the West Coast of North America.

By Marie Cachera
Moss Landing Marine Laboratories
8272 Moss Landing Road
Moss Landing, CA 95039
mcachera@mlml.calstate.edu

 

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