A piscivore () is a carnivorous animal that primarily eats fish. Fish were the diet of early tetrapod evolution (via water-bound during the Devonian period); insectivory came next; then in time, the more terrestrially adapted and evolved herbivory.
Almost all predatory fish (most , tuna, , Esox etc.) are obligated piscivores. Some non-piscine , such as , , and , are not completely piscivorous; often also preying on , , and even wading in addition to fish, while others, such as the bulldog bat and gharial, are strictly dependent on fish for food. Some creatures, including , octopuses, squid, , , , , wolves, , and , may have fish as significant if not dominant portions of their diets. can live on fish-based diets, as can their carnivorous such as and .
Etymology
The name
piscivore is derived . Piscivore is equivalent to the
Ancient Greek-derived word
ichthyophage, both of which mean "fish eater".
Discussion
The ecological effects of piscivores can extend to other
Food chain. 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
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
Birds
Fish
Mammals
Reptiles
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:
Fish
-
Diplomystus (a small clupeomorph, numerous fossils of individuals that died while trying to swallow other fishes, including smaller individuals of the same species, are known)
-
Thyrsocles (fossil specimen found with the stomach stuffed with the extinct herring Xyne)
[David, Lore Rose. January 10, 1943. Miocene Fishes of Southern California The Society p 104–115]
-
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 that had a crocodile-like skull, and scales of the lepidotes Scheenstia have been found in a skeleton where the stomach should be)
-
Elasmosaurus (long neck, stereoscopically positioned eyes, and long teeth are thought to be adaptations for stalking and trapping fish and other schooling animals)
-
Laganosuchus (flattened head suggests that it passively waited for fish to swim near its mouth in order to engulf them)
-
Ornithocheirus (hypothesized to be piscivorous due to anatomy of its jaws and dentition)
-
Pteranodon (remains of fish found in the beaks and stomach cavities of some specimens)
-
Spinosaurus (close relative of Baryonyx, is hypothesized to have preyed on fish because of giant found in the same environment, and due to anatomical features, including a mechanoreceptor snout that could have detected movements of swimming prey)
-
Titanoboa (multiple cranial and biochemical characteristics suggest it was primarily piscivorous)
