Australian ghostshark facts for kids
Quick facts for kids Australian ghostshark |
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| Australian ghostshark at the Melbourne Aquarium | |
| Conservation status | |
| Scientific classification | |
| Genus: |
Callorhinchus
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| Species: |
milii
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The Australian ghostshark (Callorhinchus milii) is a unique type of fish. It's often called the elephant shark because of its long, flexible snout. Other names include makorepe (in Māori), whitefish, or plough-nose chimaera.
This fish is a cartilaginous fish. This means its skeleton is made of tough cartilage, not bone. Sharks, rays, and skates are also in this group. You can find the Australian ghostshark in the waters off southern Australia, including Tasmania. It also lives south of East Cape and Kaipara Harbour in New Zealand. They usually live in depths from 0 to 200 meters (0 to 656 feet).
Contents
Amazing Features of the Australian Ghostshark
The Australian ghostshark has a shiny, silvery body. It often has cool, dark patterns on its sides. Its body is long and smooth, shaped like a torpedo. It has two triangular fins on its back that are far apart.
Size and Growth
Male ghostsharks grow to about 50 cm (20 inches) long. Females are larger, reaching about 70 cm (28 inches). The longest recorded ghostshark from head to tail was about 1.5 meters (5 feet) long! These fish can live for up to 15 years.
What They Eat
Ghostsharks use their special hoe-shaped snouts to search the ocean floor. They dig around for small creatures without backbones, like worms or crabs. They also eat small fish.
Laying Eggs
From spring to autumn, adult ghostsharks move closer to shore. They go into estuaries and bays to lay their eggs. Females lay their eggs on sandy or muddy areas. The eggs are inside large, yellowish capsules. After a few months, the capsule opens a little to let seawater in. Young ghostsharks hatch after six to eight months. They are about 12 cm (4.7 inches) long when they emerge.
Special Senses and Spine
Like humans, this fish has three types of cone pigments. This means they can see colors! The fin on its back has a very sharp spine. Some people think this spine might be venomous. However, no serious injuries from it have ever been reported.
Where Do Ghostsharks Live?
Currently, we know that Australian ghostsharks live in the waters around southern Australia and New Zealand. Scientists think the ghostsharks in New Zealand might be a bit different from those in Australia. More research is being done to confirm this.
Fishing for Ghostsharks
People fish for Australian ghostsharks in both New Zealand and Australia.
Commercial Fishing
In New Zealand, they are caught by commercial fishing boats. This happens especially in spring and summer. That's when the fish swim into shallower waters near the coast. In Australia, they are sometimes caught by accident in nets meant for other sharks. Fishermen might throw them back because they don't sell for as much money.
Recreational Fishing
The Australian ghostshark is also popular with people who fish for fun. They are often caught in Westernport Bay in Victoria, Australia. They are also popular in the coastal waters of south-east Tasmania.
On Your Plate
The white meat of the ghostshark is very popular. In New Zealand, it's often used in fish-and-chips restaurants. In Australia, it's sold as 'flake' or 'whitefish'.
Studying the Ghostshark's DNA
Scientists are very interested in the Australian ghostshark's genome. A genome is like a complete instruction book for building an organism. In 2014, a big science journal called Nature shared some exciting news. They found that ghostsharks are missing a certain group of genes. These genes usually help turn cartilage into bone. This discovery helps us understand how bones developed in animals with backbones.
Why Study This Fish?
The Australian ghostshark is special because it has a relatively small genome. It's about 910 megabases long. This is much smaller than the human genome, which is about 3000 megabases. Cartilaginous fish like the ghostshark are the oldest group of jawed animals with backbones. By studying their genome, scientists can learn a lot about how the genomes of all vertebrates, including humans, have changed over millions of years. We shared a common ancestor with the ghostshark about 450 million years ago!
Scientists have found that the order of genes in the ghostshark's DNA is quite similar to humans. This is even more similar than to some other fish like pufferfish or zebrafish. The Elephant Shark Genome Project is working to map out the entire genome of this amazing fish.
Protecting the Ghostshark
The New Zealand Department of Conservation has looked at the Australian ghostshark's numbers. They have classified it as "Not Threatened." This means it's not currently in danger of disappearing. They even note that its population is "Increasing," which is great news!
See Also
- Froese, Rainer, and Daniel Pauly, eds. (2006). "Callorhinchus milii" in FishBase. January 2006 version.
- Tony Ayling & Geoffrey Cox, Collins Guide to the Sea Fishes of New Zealand, (William Collins Publishers Ltd., Auckland, New Zealand 1982) ISBN: 0-00-216987-8
- Nelson, J. S. Fishes of the world (Wiley, New York 2006)
- P. R. Last and J. D. Stevens Sharks and Rays of Australia (Intl Specialized Book Service Inc. June 1991) ISBN: 978-0-643-05143-0
- Venkatesh B, Kirkness EF, Loh YH, Halpern AL, Lee AP, et al. (2007) Survey Sequencing and Comparative Analysis of the (Callorhinchus milii) Genome. PLoS Biol 5(4): e101
- Katsu, Y., Kohno, S., Oka, K., Lin, X., Otake, S., Pillai, N. E., ... & Baker, M. E. (2019). Transcriptional activation of elephant shark mineralocorticoid receptor by corticosteroids, progesterone, and spironolactone. Science Signaling, 12(584), eaar2668.
- Katsu, Y., Kohno, S., Oka, K., Lin, X., Otake, S., Pillai, N. E., ... & Baker, M. E. (2018). Transcriptional Activation of Elephant Shark Mineralocorticoid Receptor by Corticosteroids, Progestins and Spironolactone. BioRxiv, 265348.
- View the calMil1 genome assembly in the UCSC Genome Browser.
