Not All Skates Have Wheels

by Gail Wellenstein, Kitsap Beach Naturalist

Amblyraja Hyperborea, Skate. Photo credit: wikipedia/commons/7/73/Amblyraja_hyperborea1.jpg

It’s spring, time to take the new cohort of beach naturalists out for a walk at Shine Tidelands. We explore the various habitats, discussing the organisms that prefer each neighborhood. After an hour, we let everyone explore on their own, assisting whenever a beach walker is puzzled. Suddenly there is a shout, “What IS this?” The group crowds around a fleshless pile of wing shaped cartilage, with an oval mouth filled with multiple rows of triangular sharp teeth, and a one-foot long barbed tail. Although it looks like a creature from the movie “Alien,” it is actually a Big Skate, a resident of the shallower sandy bottoms of the Salish Sea. Our find is a small Big Skate, maybe two feet long, while they can get up to eight feet and two hundred pounds.

Skates are closely related to sharks and rays. They have in common a flexible cartilage skeleton and a sinister appearance. Imagine skates to be like flattened sharks, with a kite-shaped body, wing-like pectoral fins, mouth and gills on the bottom and eyes on top. This body plane is shared by rays, but skates lack venomous spines, have shorter, thicker tails and lay eggs, while most rays give birth to live young. Another difference is their choice of environment. Rays are like Jimmy Buffet, hanging out in the warmer tropical waters, while skates tough it out in the cooler temperate to polar zones.

Skates are among the most mysterious creatures living beneath the waters of the Salish Sea. They glide silently across sandy bottoms and muddy channels, relying on camouflage for protection from large bony fish and sharks. The Big Skate, the most common species in our area, will bury itself in the sand or mud, leaving only its eyes visible, as it patiently waits for a dinner consisting of shrimp, worms, clams, and small fish. Special openings behind the eyes allows it to breathe while hidden beneath the sediment.

Despite skates being common residents of the Salish Sea, many people encounter them only accidentally while fishing or beachcombing. Perhaps the most common evidence for skates is finding a “Mermaid Purse” on the beach. This is a large oblong egg capsule, with a broad horn at each corner. One capsule typically holds three or four Big Skate eggs that take nine months to develop. It will take between eight and twelve years for a skate to reach sexual maturity, leaving only a few years of reproduction until they reach their lifespan of 15 to 25 years.

Skates offer a glimpse into the quieter side of the Salish Sea. They are not dramatic like their shark cousins, but they do have important roles in the marine environment. They make nutrients available to other organisms by stirring up the sediment when they hide on the bottom. They are important members of the marine food chain, eating shellfish and small fish, and in turn provide food to larger fish and sharks. Some of you may have eaten skate wings in France where they are popular for their firm, mild, and slightly nutty flavor, comparable to scallops. This video gives a fascinating glimpse into The World of Deep Sea Rays and Skates, at youtube.com/watch?v=T8j1yzP4ifE