Gecko catshark facts for kids
Quick facts for kids Gecko catshark |
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| Conservation status | |
| Scientific classification | |
| Genus: |
Galeus
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| Species: |
eastmani
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| Range of the gecko catshark | |
| Synonyms | |
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Pristiurus eastmani D. S. Jordan & Snyder, 1904 |
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The gecko catshark (Galeus eastmani) is a type of catshark. It belongs to the family called Scyliorhinidae. This shark lives in the northwestern Pacific Ocean, from southern Japan all the way to Taiwan. It might also be found off the coast of Vietnam.
This shark is quite common. It lives near the sea floor at depths of about 100 to 900 meters (330 to 3,000 feet). The gecko catshark has a slender body with dark saddle-like markings and blotches. Its dorsal (top) and caudal fin (tail) fins have white edges. It also has a special bumpy ridge of enlarged dermal denticles (tiny, tooth-like scales) along the top edge of its tail fin.
Gecko catsharks often swim in groups. They are predators that hunt different kinds of food, like bony fishes, cephalopods (like squid), and crustaceans (like shrimp and crabs). These sharks are oviparous, which means the females lay eggs. They usually lay two vase-shaped egg capsules at a time.
Sometimes, gecko catsharks are caught by accident by fishing boats. This is called bycatch. However, they don't seem to be in danger from fishing right now. The International Union for Conservation of Nature (IUCN) has listed them as a species of Least Concern.
Contents
What's in a Name?
The gecko catshark's scientific name, eastmani, might be a tribute to a fish paleontologist named Charles Rochester Eastman (1868-1918). Paleontologists study ancient life, like fossils!
Discovery and Shark Family Tree
The first gecko catshark ever studied was a female about 35 centimeters (14 inches) long. It was caught near the Izu Peninsula in Japan. An important shipmaster named Alan Owston gave this shark to two American ichthyologists (fish scientists), David Starr Jordan and John Otterbein Snyder.
Jordan and Snyder officially described this new species in 1904. They first named it Pristiurus eastmani. Later, scientists realized that Pristiurus was actually the same as the Galeus group of sharks. So, the gecko catshark became known as Galeus eastmani.
Scientists have also studied the shark's DNA to understand its family tree. They found that the gecko catshark is closely related to other sharks like the slender sawtail catshark and the blacktip sawtail catshark.
Where They Live
The gecko catshark lives in the ocean from southern Japan, including areas like Shizuoka and Mie Prefecture on Honshu island, and the main islands of Shikoku and Kyushu. They are also found in the East China Sea, near Taiwan. There are many of these sharks in Japanese waters. Some reports say they are also found off Vietnam, but this is not fully confirmed.
These sharks live in waters from 100 to 900 meters (330 to 3,000 feet) deep. They stay on or very close to the sea floor. Interestingly, male and female gecko catsharks might live in different areas of the ocean.
What They Look Like
The gecko catshark can grow up to 40 centimeters (16 inches) long, and possibly even 50 centimeters (20 inches). It has a slim, firm body and a fairly short head. The snout (nose) is flat with a blunt tip.
Their nostrils are large and have small flaps of skin. The eyes are big and shaped like horizontal ovals. They have special protective eyelids called nictitating membranes, which are like a third eyelid. The mouth is quite large and curved.
Inside their mouths, they have many small teeth. There are about 47 rows of teeth in the upper jaw and 50 rows in the lower jaw! Each tooth has a narrow point in the middle and usually two smaller points on each side. They have five pairs of short gill slits, which help them breathe underwater.
The first dorsal fin (on its back) is blunt and sits above the back half of its pelvic fins (fins near its belly). The second dorsal fin is similar but a bit smaller. The pectoral fins (side fins) are large and wide with rounded edges. The pelvic fins are small. Adult male sharks have special parts called claspers, which are short and don't reach their anal fin.
The caudal peduncle (the narrow part connecting the body to the tail) is almost round. The caudal fin (tail fin) is low, with a small lower part and a notch near the tip of the upper part.
Their skin is covered in tiny, overlapping dermal denticles. These are like small, tooth-shaped scales. Each one has a leaf-shaped top with a ridge and three small teeth. There's also a ridge of larger denticles along the top edge of the tail fin.
Gecko catsharks are grayish on top. They have darker, fuzzy-edged saddle shapes and blotches along their body and tail. Their underside, the edges of their dorsal and caudal fins, and the inside of their mouth are white.
Life Cycle and What They Eat
Gecko catsharks often swim in groups, which is called schooling. They are not picky eaters and will hunt a variety of foods. Their diet includes different kinds of bony fishes (like lanternfish), cephalopods (such as small squid), and crustaceans (like isopods, amphipods, krill, and decapods like crabs and shrimp). What they eat most depends on where they are and the time of year, as they eat what is most available.
These sharks are oviparous, meaning they lay eggs. Female gecko catsharks have one working ovary (on the right side) and two working oviducts (tubes where eggs develop). Only one egg develops in each oviduct at a time.
The mature eggs are inside smooth, clear yellow, vase-shaped capsules. These capsules are about 6 centimeters (2.4 inches) long and 1.6 centimeters (0.6 inches) wide. The top is squared off, and the bottom narrows into a short point.
One study in Suruga Bay found that females had large eggs in their ovaries all year. However, females in the western part of the bay only carried egg cases from October to January. This might mean they lay eggs more often during those months.
Male gecko catsharks become ready to reproduce when they are about 31 to 32 centimeters (12 to 12.6 inches) long. Females are ready when they are about 36 to 37 centimeters (14 to 14.6 inches) long. However, one male shark found in Taiwan was 38 centimeters (15 inches) long but was not yet mature.
Gecko Catsharks and People
Sometimes, gecko catsharks are caught by accident in commercial trawl fisheries. This is called bycatch. In Taiwan, they are sometimes sold in markets and turned into fishmeal, which is used to feed fish in aquaculture (fish farming).
Because these sharks are small and lay eggs, they might be able to handle fishing pressure better than some other shark species. The gecko catshark is still common off Japan. Also, they might be safe from fishing in the deeper parts of their habitat. For these reasons, the International Union for Conservation of Nature (IUCN) has decided that the gecko catshark is a species of Least Concern. This means they are not currently in danger of disappearing.
Images for kids
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A drawing of a gecko catshark.
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Map showing where the gecko catshark lives.
