Spiny Dogfish

March 28th, 2015 No comments

Spiny Dogfish

Spiny Dogfish

Squalus acanthias

Like wild dogs on land, spiny dogfish hunt in packs in the sea. These small sharks devour large numbers of herring, salmon, and other valuable commercial fish. They also tear at fishing nets and bite off bait and hooks from fishing lines.

The spiny dogfish serves many useful purposes, however. Many Europeans consider the dogfish good eating. There it is sold frozen, smoked, and salted, and is made into fish-and-chip dinners. The spiny dogfish’s skin is covered with tiny bumps, called "denticles," which give it the feel of fine sandpaper. When dried, the skin can be used to polish wood or as a rough kind of leather. In North America, many high school students know the spiny dogfish from biology class. The shark’s body is often dissected during anatomy lessons. The spiny dogfish has two long spines on its dorsal fins. These spines probably discourage larger fish from biting. The spiny dogfish’s enemies include humans, swordfish, and larger species of shark.

Although not endangered, the spiny dogfish is becoming rare. The species may not be able to recover well from overfishing, because it reproduces slowly. Adult females give birth only once every two years. The newborns are often eaten by larger fish. Young dogfish also mature very slowly, and do not have babies of their own until they are six to 20 years old.

class: Sharks and rays

order: Dogfish sharks

family: Dogfish sharks

length: 28 to 40 inches

diet: small fish, squid, shrimp, sea anemones, jellyfish, and algae

number of young: 6

home: oceans worldwide


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Categories: Freshwater Fish Tags:


March 27th, 2015 No comments



Pterois volitans
It’s easy to see that the zebrafish was named for its brilliant stripes. It is also called the lionfish for its frilly "mane." But scuba divers had better beware—this lion has poison-tipped spikes in its flowing mane. The zebrafish’s venom stings like a bee’s. It can make a person’s hand swell painfully, or it can even kill another fish.

The zebrafish uses its 6-inch-long quills to defend itself from enemies. Most of the spikes point to the sides and to the back. This protects the zebrafish from being attacked from behind. Despite its fearsome weapons, a zebrafish will generally try to avoid a fight. However, biologists have found that when harassed, the zebrafish points its spikes forward and charges.

The zebrafish probably evolved its bright stripes to remind its enemies of its poison. A predator that doesn’t know better may attack a zebrafish—so that both animals come away injured. But the zebrafish’s attacker will remember the vicious sting along with the brilliant stripes. It will now know better than to ever attack another zebrafish.

The zebrafish’s favorite method of hunting is to hang upside down in a dark cave. With its large, powerful eyes, the zebrafish can easily spot smaller fish swimming in the darkness. It then chases its prey into a corner and sucks the meal down with one gulp.

class: Bony fishes
order: Mail-cheeked fishes
family: Scorpion fishes

length of the body: 15 inches

weight: 2 pounds

diet: fish and invertebrates

number of eggs: thousands

home: Indian and West Pacific oceans


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  • Spiny Dogfish
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Categories: Freshwater Fish Tags: ,