Piscivore

A piscivore (/ˈpɪsɪvɔːr/) is a carnivorous animal that mainly eats fish. Many animals, both in water and on land, rely on fish as a big part of their food. Fish were an important food source for early tetrapod evolution, starting with water-bound amphibians during the Devonian period. Later, animals that lived more on land, like reptiles and synapsids, began to eat plants as well.

Almost all predatory fish, such as most sharks, tuna, billfishes, and pikes, are piscivores because they need to eat fish to survive. Some other animals, like whales, sea lions, and crocodilians, also eat fish but will eat other things too, like invertebrates, marine mammals, and even land animals. There are animals such as the bulldog bat and gharial that depend only on fish for food.

Even animals you might not expect, like grizzly bears, jaguars, wolves, snakes, turtles, and sea gulls, will eat fish when they can. Humans can live mainly on fish, and even some domesticated pets like dogs and cats can have fish as a big part of their diet.

Etymology

The word piscivore comes from Latin words: piscis, meaning "fish," and vorō, meaning "to devour." This is similar to the Greek word ichthyophage, which also means "fish eater."

Discussion

Piscivores, animals that eat fish, can affect other parts of nature. For example, adding cutthroat trout to a lake can change what bats eat, because the bats eat insects that come out of the water where the trout live. In another case, removing lionfish helps keep coral reefs healthy, and counting piscivores can show how well the reefs are doing.

Some animals become fish-eaters early in life, called primary piscivores. Others start eating fish later, called secondary piscivores. Scientists think this change helps these animals use energy better as they grow.

Examples of extant piscivores

Some animals eat mainly fish.

Arachnids

• Fishing spider

Birds

• Bald eagle
• Merganser
• Osprey
• Penguin

Fish

• African tigerfish
• Alligator gar
• Arapaima
• Barracuda
• Bluefish
• Giant trevally
• Kidako moray
• Lemon shark
• Lionfish
• Piranha
• Silver arowana

Mammals

• Amazon river dolphin
• American mink
• Aquatic genet
• Bottlenose dolphin
• Bulldog bat
• Eurasian otter
• Fish-eating bat
• Fishing cat
• Flat-headed cat
• Fur seal
• Giant otter
• Harbor seal
• North American river otter
• Orca
• Otter shrew
• Sea lion
• Tiger

Reptiles

• Asian water monitor
• Gharial
• Green anaconda
• Komodo dragon
• Yellow anaconda
• Yellow-bellied sea snake

Extinct and prehistoric piscivores

Many ancient animals are thought to have mainly eaten fish, based on their body shape or where they lived. Some of these animals have been proven to eat fish because scientists found fish inside their fossil remains. This list includes both specialist fish-eaters and general predators that ate fish.

Fish

• Diplomystus (a small relative of the herring, many fossils show these fish died trying to eat other fishes, including smaller ones of their own kind)
• Thyrsocles (a fossil was found with its stomach full of the extinct herring Xyne grex)
• Xiphactinus (a 4-meter-long specimen was found with a perfectly preserved skeleton of its relative, Gillicus, in its stomach)

Reptiles

• Baryonyx (an opportunistic predator with a crocodile-like skull, and scales of the lepidotid fish Scheenstia have been found where its stomach would be)

• Elasmosaurus (its long neck, special eyes, and long teeth are thought to help it catch fish and other schooling animals)

• Laganosuchus (its flattened head suggests it waited for fish to swim close so it could catch them)

• Ornithocheirus (thought to eat fish based on the shape of its jaws and teeth)

• Pteranodon (some specimens have fish remains in their beaks and stomachs)

• Spinosaurus (a close relative of Baryonyx, it is thought to have eaten fish because giant coelacanthids lived in the same area, and it had special features like a pressure-sensitive snout to sense moving prey)

• Titanoboa (its skull and body features suggest it mainly ate fish)