Piscivore


A piscivore is a carnivorous animal that primarily eats fish. Fish were the diet of early tetrapod evolution ; insectivory came next; then in time, the more terrestrially adapted reptiles and synapsids evolved herbivory.
Almost all predatory fish are obligated piscivores. Some non-piscine aquatic animals, such as whales, sea lions, and crocodilians, are not completely piscivorous; often also preying on invertebrates, marine mammals, waterbirds and even wading land animals in addition to fish, while others, such as the bulldog bat and gharial, are strictly dependent on fish for food. Some creatures, including cnidarians, octopuses, squid, cetaceans, spiders, grizzly bears, jaguars, wolves, snakes, turtles and sea gulls, may have fish as significant if not dominant portions of their diets. Humans can live on fish-based diets, as can their carnivorous domesticated pets such as dogs and cats.

Etymology

The name piscivore is derived. Piscivore is equivalent to the Greek-derived word ichthyophage, both of which mean "fish eater".

Discussion

The ecological effects of piscivores can extend to other food chains. In a study of cutthroat trout stocking, researchers found that the addition of this piscivore can have noticeable effects on non-aquatic organisms, in this case bats feeding on insects emerging from the water with the trout. Another study done on lionfish removal to maintain low densities used piscivore densities as a biological indicator for coral reef success.
There exist classifications of primary and secondary piscivores. Primary piscivores, also known as "specialists", shift to this habit in the first few months of their lives. Secondary piscivores will move to eating primarily fish later in their lifetime. It is hypothesized that the secondary piscivores' diet change is due to an adaptation to maintain efficiency in their use of energy while growing.

Examples of extant piscivores

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

Numerous extinct and prehistoric animals are hypothesized to have been primarily piscivorous due to anatomy and/or ecology. Furthermore, some have been confirmed to be piscivorous through fossil evidence. This list includes specialist piscivores, such as Laganosuchus, as well as generalist predators, such as Baryonyx and Spinosaurus, found to have or assumed to have eaten fish:
Image:Diplomystus Vienna.jpg|thumb|right|Specimen of Diplomystus swallowing another fish

Fish

  • Diplomystus
  • Thyrsocles
  • ''Xiphactinus''

    Reptiles

  • Baryonyx
  • Elasmosaurus
  • Laganosuchus
  • Ornithocheirus
  • Pteranodon
  • Spinosaurus
  • ''Titanoboa''