Slender sawtail catshark facts for kids
Quick facts for kids Slender sawtail catshark |
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Galeus
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gracilis
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| Range of the slender sawtail catshark | |
The slender sawtail catshark (Galeus gracilis) is a type of catshark. It belongs to the Scyliorhinidae family. This shark lives only in northern Australia. It can be found deep in the ocean, on the continental slope, between 290 and 470 meters (about 950 to 1,540 feet) down.
This shark grows to about 34 centimeters (13 inches) long. It has a slender gray body. You can spot it by the four dark saddle-like markings. These are found below its dorsal fins and on its caudal fin (tail fin). It also has a special ridge of large, tooth-like scales along the top edge of its tail fin. People don't fish for the slender sawtail catshark. However, it sometimes gets caught by accident in fishing nets. Scientists don't have enough information yet to know if it's in danger.
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Meet the Slender Sawtail Catshark: Its Name and Family Tree
Scientists Leonard Compagno and John Stevens first described this shark in 1993. They published their findings in a science magazine called Records of the Australian Museum. They named it gracilis, which means "slender" in Latin. This name perfectly describes the shark's slim body. Before this, it was just called Galeus sp. A.
The first shark studied was a 34-centimeter (13-inch) long adult female. It was caught near Melville Island in January 1988. The slender sawtail catshark is closely related to other sharks in its group. These include the gecko catshark (G. eastmani), the longnose sawtail catshark (G. longirostris), and the broadfin sawtail catshark (G. nipponensis).
In 2005, scientists studied the shark's DNA. They found that the slender sawtail catshark, the gecko catshark, and the blacktip sawtail catshark (G. sauteri) are a special group. They are different from other sharks like the blackmouth catshark (G. melastomus) and the mouse catshark (G. murinus).
What Does the Slender Sawtail Catshark Look Like?
This is a small shark, growing to at least 34 centimeters (13 inches) long. It has a slender body that is almost round. Its head is short and narrow, with a rounded snout. The shark's eyes are oval-shaped. They have small, protective third eyelids, like some other animals. Below each eye, there's a thin ridge. Behind the eyes, there's a tiny hole called a spiracle.
The shark's nostrils are split by small, triangle-shaped skin flaps. Its mouth is wide and curved. It has grooves around the corners. The teeth are small and packed closely together. There are 54 to 57 rows of teeth in the upper jaw. The lower jaw has 54 to 62 rows. Each tooth has a narrow point in the middle. It usually has one or two smaller points on each side. Male sharks have slightly larger and longer teeth than females. This shark has five pairs of gill slits. The last two pairs are above the bases of its pectoral fins.
Fins and Skin of the Slender Sawtail Catshark
The first dorsal fin (on its back) is a bit larger than the second one. It starts above the middle of the pelvic fin bases. The second dorsal fin is located over the back part of the anal fin. Both dorsal fins have rounded tips. The pectoral fins are short, wide, and somewhat triangular. The pelvic and anal fins are long and low, with sharp angles.
Adult male sharks have long, pointed claspers. These are special organs used for reproduction. Each clasper has rows of saw-like scales on the inside. The tips are twisted. The base of the anal fin is about 11% of the shark's total length. It is as long as or longer than the space between the anal fin and the pelvic and caudal fins. The caudal fin (tail fin) is narrow. It has a small lower part and a notch near the tip of the upper part.
The shark's body and fins are covered in tiny, overlapping dermal denticles. These are like small, tooth-like scales. Each denticle has a teardrop shape with small pits. It also has a central ridge and usually three small teeth on its edge. There is a special ridge of larger denticles along the front part of the tail fin's top edge.
The slender sawtail catshark is light gray on top and lighter underneath. It has a small, dark saddle mark below each dorsal fin. There are also two more saddle marks on the tail fin. The second one almost forms a complete ring. Some sharks might also have a faint dark spot on each side. The inside of its mouth is dark gray.
Where Does the Slender Sawtail Catshark Live?
The slender sawtail catshark seems to be rare. It has been found in a few places around Australia. These include off Cape Cuvier and Port Hedland in Western Australia. It has also been seen off Melville Island in the Northern Territory and off Cape York in Queensland. It might also live in the eastern waters of Indonesia. Scientists don't know if these sightings mean there are many separate groups of sharks or just one big group.
This shark lives on the ocean floor, deep on the continental slope. It prefers depths between 290 and 470 meters (about 950 to 1,540 feet).
Life Cycle of the Slender Sawtail Catshark
Not much is known about the daily life of the slender sawtail catshark. We do know that male sharks become ready to reproduce when they are about 33 centimeters (13 inches) long.
How Do Humans Interact with This Shark?
Some slender sawtail catsharks are caught by accident. This happens in the Western Trawl Fishery, which operates off northwestern Australia. People do not specifically fish for this shark because it has no commercial value.
The International Union for Conservation of Nature (IUCN) is an organization that studies animal populations. They don't have enough information about threats to this species. Because of this, they have listed the slender sawtail catshark as Data Deficient. This means more research is needed to understand its conservation status.
See also
In Spanish: Galeus gracilis para niños
