Big skate
The big skate, a notable flat-bodied fish native to the North American Pacific Ocean, is the largest among over 200 species of skates, potentially reaching lengths over eight feet (2.5 meters) and weights up to 200 pounds (90 kilograms). Typically found in coastal waters ranging from Baja California to the Bering Sea, these skates thrive in soft-bottomed environments at depths of 10 to 360 feet (3 to 110 meters), allowing them to bury themselves while awaiting prey. The big skate features a distinctive diamond-shaped body with broad, wing-like pectoral fins that enable graceful movement, resembling flight as it glides along the ocean floor.
Physically, its coloration varies from olive brown or green above with light spots to a white underside, and it possesses unique eyespots on its fins. Big skates primarily hunt by smell, consuming a variety of marine life, including crabs, lobsters, and small fish. Although they have natural predators like sharks and elephant seals, they face threats from human activities, particularly overfishing. The reproductive process involves the female laying rectangular egg cases known as mermaid's purses, which hatch after several months. With a lifespan of 15 to 25 years, the big skate's conservation status is considered near threatened in some regions.
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Big skate
The big skate is native to the waters of the North American Pacific Ocean. The big skate is the largest of the over 200 species of these flat-bodied fish. It may grow to be over eight feet (2 1/2 meters) long and weigh up to 200 pounds (90 kilograms).
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: Rajiformes
Family: Rajidae
Genus: Beringraja
Species: Binoculata
The big skate makes its home in the coastal waters from Baja California north to the Bering Sea. It generally swims along the bottom in depths of 10 to 360 feet (3 to 110 meters) where the bottom is soft, either sandy or muddy. The soft bottom is ideal for burying itself as it waits for prey.
The big skate's body is flattened and disk-like. It is somewhat like the shape of a diamond, except that the two rear edges of its body are slightly rounded. The long, fleshy tail extends from the body where the fourth point of the diamond would be. It has broad, wing-like pectoral fins which extend from either side of the body and look as though they make up the entire body itself. The fins allow the skate to swim gracefully as though it were flying. At other times it may appear to walk along the bottom on its fin tips. The big skate may be olive brown or green above with light spots and white on its underside. The top surface of each large pectoral fin also has a dark spot with a white ring around it. These spots are called eyespots or ocelli (singular ocellus). An adult may reach over eight feet (2 1/2 meters) in length and weigh up to 200 pounds (90 kilograms). The average size of a big skate, however, is closer to six feet (1.8 meters).
When it is swimming, the skate breathes by taking in water through its mouth. After it removes the oxygen from the water, it pushes the water from its five sets of gill openings on its underside. When it is lying buried in the sand, it breathes through openings called spiracles on its back behind its eyes. In this way it does not get sand and mud in its mouth, nostrils, and gills.
A row of large thorns runs along the middle of the skate's back to the first of its two dorsal, or back, fins. Other smaller thorns are located between its eyes, and there is one thorn in the middle of its back behind the spiracles, or openings through which it takes in water. These thorns provide some protection from predators or intruders. The tail is also able to produce a weak electrical charge of four volts. This is not likely used in defense as much as it may be used in courtship and mating.
Even though the big skate has good vision, it hunts more by smell than by sight, either during the day or the night. The skate pounces upon crabs, lobsters, crustacea, and shrimp as it glides across the bottom. It may also seize small fish, such as gunnards, flatfish, anglerfish, herring, scad, and pilchard. Small squid occasionally find themselves overshadowed by the body of the skate as it swoops in to grab them in its teeth. Mollusks lying on the bottom are easy prey for the skate to catch and to crush.
Humans present some danger to the skate due to overfishing. The wing-like fins are eaten in some places. Natural predators include species of shark. Elephant seals often prey on skate eggs.
The female big skate lays an egg case called a mermaid's purse. Each case is rectangular, possibly up to one foot (30 centimeters) long, and has a leather-like surface. Some egg cases may have a long tendril hanging from each corner which anchors the case to seaweed or rocks. After six to nine months, two to seven baby big skates hatch from the case.
The life span of the big skate is between 15 and 25 years.
The big skate is a member of the class of cartilaginous fish, or those fish which do not have skeletons of bones but of cartilage.
The big skate may be considered near threatened in some areas.
Bibliography
Bester, Cathleen. “Raja Binoculata – Discover Fishes.” Florida Museum, 1 Jan. 2024, www.floridamuseum.ufl.edu/discover-fish/species-profiles/raja-binoculata. Accessed 20 Mar. 2024.
“Big Skate.” Monterey Bay Aquarium, 2024, www.montereybayaquarium.org/animals/animals-a-to-z/big-skate. Accessed 20 Mar. 2024.