Squalidae
Quick facts for kids Dogfish sharks |
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| The Spiny dogfish, also known as Squalus acanthias | |
Scientific classification  |
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| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Order: | Squaliformes |
| Family: | Squalidae Bonaparte, 1834 |
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Dogfish sharks, also known as dogfish or spiny dogfish, are a fascinating group of sharks. They belong to a family called Squalidae. These sharks are part of a larger group called Squaliformes, which is the second-largest order of sharks, with 119 different species across 7 families!
They got their name because some fishermen once saw them chasing smaller fish in groups, much like a pack of dogs. Dogfish sharks have sleek, streamlined bodies that are often more compact than other shark species. They also have a pointed snout.
Contents
Amazing Dogfish Sharks
How Do Dogfish Sharks Look?
Dogfish sharks have two dorsal fins, which are the fins on their back. Each of these fins has smooth spines. However, they do not have an anal fin, which is a fin found on the underside of some fish. Their skin feels rough if you touch it.
When they grow up, male dogfish sharks usually reach about 99 centimeters (39 inches) long. Females are typically larger, growing to about 124 centimeters (49 inches) long. This difference in size between males and females is called sexual dimorphism.
Their skin is usually a slate-grey or grey-brown color, often with white dots. Their belly area is much paler, almost white. Dogfish sharks have teeth in both their upper and lower jaws that are similar in size. They also have a special part near their tail called a caudal peduncle with side ridges, and their caudal fin (tail fin) does not have a small notch at the end.
What Do Dogfish Sharks Eat?
Dogfish sharks are carnivores, meaning they eat meat. They mostly hunt and eat organisms smaller than themselves. Some of their favorite meals include herring, mackerel, and capelin. Sometimes, they might even snack on jellyfish and squid. Even young dogfish pups are skilled hunters and can catch fish two or three times their own size! They use their strong jaws and sharp teeth to grab and eat their prey.
Special Abilities and Records
Unlike most other sharks, dogfish sharks have a unique defense! Their dorsal spines (the pointy parts on their backs) are covered with a mild venom. If a dogfish shark is mishandled or accidentally touched, this venom could cause some discomfort. So, it's always best to admire these amazing creatures from a safe distance and never try to touch them!
A Long Journey and Long Pregnancy
The spiny dogfish is known for breaking some impressive records. These sharks are great travelers! One shark was tagged in Washington state, United States, and later found all the way in Japan, having traveled about 8,047 kilometers (5,000 miles)!
They also hold the record for the longest pregnancy of any vertebrate animal. A female dogfish shark carries her babies for an incredible 22 to 24 months! That's almost two years! When the pups are born, they are already live young and measure between 20 to 33 centimeters (8 to 13 inches) long.
How Dogfish Sharks Reproduce
The way dogfish sharks reproduce is quite interesting. Females can have pups from different fathers in the same litter. This is like having siblings in a family who have the same mother but different fathers. It's a clever way for the sharks to increase their genetic diversity, which means there's a wider mix of traits in the population. This is super important for helping the species stay strong and healthy, especially because their numbers can be affected by fishing.
Dogfish Shark Families
Dogfish sharks are scientifically classified under the family Squalidae. This family is part of the larger Squaliform order, which includes seven families in total. The Squalidae family itself contains two main groups, or genera: Cirrhigaleus and Squalus. Together, these two groups include 37 different species of dogfish sharks. Scientists have also found evidence of extinct groups, like †Protosqualus.
The Squalus Family
The Squalus genus is the larger of the two, with 34 different species of dogfish. You can find these sharks in waters all around the world. Most species in this group range from 56 to 160 centimeters (22 to 63 inches) in length. One species, Squalus margaretsmithae (Smith's dogfish shark), is known to be smaller, reaching a maximum of about 54 centimeters (21.3 inches).
Most Squalus species have a slate or blue-grey body with a white belly. However, two species, the Squalus acanthias and the Squalus suckleyi, are easily recognized by their distinct, evenly-spaced small white dots on their darker backs.
The Cirrhigaleus Family
In contrast, the Cirrhigaleus genus currently includes only 3 species. The most recent one, Cirrhigaleus australis, was discovered and classified in 2007. Cirrhigaleus species are generally larger than most Squalus species, typically ranging from 119 to 126 centimeters (47 to 49.5 inches) long. (Even though the largest individual dogfish, Squalus acanthias, is in the Squalus group, most Squalus species are smaller than 99 centimeters or 39 inches).
Cirrhigaleus sharks share many features with their Squalus relatives, like a blue-grey or grey-brown body and a white belly. However, they have some key differences. Most notably, Cirrhigaleus sharks have very long nasal barbels, which are whisker-like sensory organs near their nose. They also have small black spots instead of white ones in a similar pattern.
For a full list of shark species, you can visit the list of sharks page.
