Australian grey smooth-hound facts for kids
Quick facts for kids Australian grey smooth-hound |
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| Conservation status | |
| Scientific classification | |
| Genus: |
Mustelus
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| Species: |
ravidus
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| Range of the Australian grey smooth-hound | |
The Australian grey smooth-hound, also known as the grey gummy shark (its scientific name is Mustelus ravidus), is a type of shark. Its name Mustelus ravidus means 'greyish weasel'. It belongs to a big shark family called Triakidae.
This shark is one of 28 species in the Mustelus group, which are usually small sharks. While other Mustelus sharks live in warm and mild waters around the world, the grey gummy shark lives only in the Pacific and Indian Oceans near Australia. It especially likes deep coastal waters.
The grey gummy shark gives birth to live young, just like humans do. Not much is known about its population, but scientists think it's stable. This shark is not known to be a threat to people.
Contents
About the Grey Gummy Shark
What's in a Name?
The scientific name for the grey gummy shark is Mustelus ravidus. This name comes from two Latin words. Mustela means 'weasel', and ravidus means 'grey'. So, the name literally means 'greyish weasel'. Long ago, people sometimes called sharks 'weasels'. The 'ravidus' part of the name describes the shark's grey color on its back.
Shark Family Tree
The grey gummy shark is part of the Triakidae family. This family includes sharks often called houndsharks or smooth-hounds. These sharks usually eat small creatures and fish that live on the ocean floor or in the middle of the water.
The grey gummy shark is also in the Mustelus group. Sharks in this group are often small and live near the bottom of the ocean. Scientists have found that many smooth-hound sharks look very similar. This can make it hard to tell different species apart. But the grey gummy shark is usually identified correctly. Researchers now use DNA to help tell shark species apart and learn about their family history.
Scientists have found that the grey gummy shark is closely related to two other sharks: the Andaman smooth-hound and the Arabian smooth-hound. These three sharks are special because they don't have white spots on their bodies, which helps tell them apart from other related sharks.
How Sharks Evolved
We don't have many fossils for the Mustelus group, so it's hard to know exactly how they evolved. But we do know that all Mustelus sharks give birth to live young. Some have a special connection like a placenta during pregnancy, and some don't. The grey gummy shark has this placental connection. Scientists think that having this connection might be a newer development in their evolution.
Where They Live
The grey gummy shark lives only around Australia. It likes to swim in areas near the coast and on the ocean floor. You can often find it on the continental shelves, especially off Western Australia. It usually lives at depths between 106 and 300 meters.
This depth range is often called the "twilight zone" of the ocean. The twilight zone goes from 200 meters to 1000 meters deep. Sunlight can't reach all the way down here, or only a little bit of light gets through. The grey gummy shark usually stays in the upper part of this twilight zone.
What They Look Like
General Appearance
Like most sharks in its family, the grey gummy shark has two large fins on its back and one fin underneath. It also has special eyelids that can cover its eyes. Its skin is a pale grey color, and it doesn't have any white or other colored spots.
Its fins have some unique features. The fin under its tail is wide and curved. Its back fins are slightly curved backward. The front and back dorsal fins (on its back) have white and dusky tips, respectively. The very tip of its tail fin is black. The first dorsal fin is taller and brownish, while the second one is paler in the middle. Scientists can also count the bones in a shark's spine to help tell different species apart. The grey gummy shark usually has 90 to 91 bones in its spine before the tail.
Size and Safety
The grey gummy shark has a long, thin body and is quite small. The biggest one ever found was a female shark, about 78.8 centimeters (about 31 inches) long. Male grey gummy sharks are usually smaller, growing to about 58 centimeters (about 23 inches). Female sharks are often bigger because they need more space inside to carry their babies.
Because it's small and not aggressive, the grey gummy shark is not a threat to humans. There have been no reports of these sharks interacting with people or attacking them.
Mouth and Teeth
The grey gummy shark has a fairly strong mouth with a wide arch. Its snout is somewhat pointed. Inside its mouth, it has teeth that are not perfectly even. They have dull, rounded tips.
Eyes
Grey gummy sharks have large, oval-shaped eyes. Like many animals, they have special lower eyelids that can close over their eyes. These eyelids might help protect their eyes or keep them moist underwater. This is especially useful since they live in the twilight zone, where visibility might be different.
How They Reproduce
The grey gummy shark is a placental and viviparous animal. This means the mother nourishes her babies through a special connection, like a placenta, and gives birth to live young. We don't know much about their full life cycle or how they mate. However, available information suggests that a female grey gummy shark can have between 6 and 24 pups at a time, with an average of about 18 babies per pregnancy.
Scientists have also noticed a link between whether a Mustelus shark has white spots and how it reproduces. Sharks without white spots tend to have the placental type of reproduction, while those with white spots do not have a placenta.
Conservation Status
Sharks can be affected by human activities like fishing, losing their homes, or their homes becoming polluted. In 2018, the grey gummy shark was checked by the International Union for Conservation of Nature (IUCN). It is now listed as "Least Concern" on the IUCN Red List. This means its population is thought to be stable. This is partly because it doesn't have much contact with fishing boats and doesn't face many big natural threats.
Because of this, there aren't any specific conservation plans just for the grey gummy shark. However, in 1993, shark fishing was stopped in a northern part of Western Australia. This is believed to have helped keep the shark's population stable.
Even so, the grey gummy shark can still be caught by other fishing methods. One study gave it a "fishing vulnerability" rating of 52 out of 100, where 100 is the highest risk. Also, with more people using drones for fishing, the grey gummy shark has been caught this way. In one study of drone catches in Australia, the grey gummy shark was one of the most commonly caught species (16%).
Like many fish, the grey gummy shark can be caught by accident during commercial fishing. But this doesn't happen very often. Since 2010, a fishery in Western Australia reported catching very few gummy sharks (less than three tons per year). Most of these were likely another type of gummy shark, but it's possible some grey gummy sharks were caught by accident. Another fishery in Western Australia has said they have never recorded catching grey gummy sharks.
