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What is a Fish?. What is a Fish?. Frogfish. Hairy Frogfish. Goosefish. Oarfish. Antlered Sculpin. Cowfish. Blobfish. Coffin Fish. Fangtooth. Lizardfish. Prickly Shark. Umbrella Mouth. What is a Fish?. Historic definition: Larger animals that live in the water. Toadfish.
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What is a Fish?
What is a Fish?
Phylogenetic definition: Vertebrates that occupy the phylogenetic position between cephalocordates (lancelets) and amphibians Evolution!
Amphioxus Sea Lancelet
Poison Dart Frog
Anatomic Definitions:Cold blooded vertebrates with gills and fins
Gills Fin Feet!
Lamprey Is this a fin?
Strictly aquatic craniate vertebrates typically with an elongated or somewhat spindle-shaped body terminating in a broad caudal fin, limbs in the form of fins when present at all, and a 2-chambered heart by which blood is sent through thoracic gills to be oxygenated
Strictly aquatic craniate vertebrates typically with an elongated or somewhat spindle-shaped body terminating in a broad caudal fin, limbs in the form of fins when present at all, and a 2-chambered heart by which blood is sent through thoracic gills to be oxygenated
Strictly aquatic craniate vertebrates typically with an elongated or somewhat spindle-shaped body terminating in a broad caudal fin, limbs in the form of fins when present at all, and a 2-chambered heart by which blood is sent through thoracic gills to be oxygenated
Spindle Shape Broad Caudal
Strictly aquatic craniate vertebrates typically with an elongated or somewhat spindle-shaped body terminating in a broad caudal fin, limbs in the form of fins when present at all, and a 2-chambered heart by which blood is sent through thoracic gills to be oxygenated
Aristotle’s (Greek philosopher and scientist) definition in “Historia Animalium” 340 BC: To begin with, fishes have a head, dorsal and ventral sides; in the last named situation are placed the belly and viscera; and at the rear fishes have a tail which is continuous and undivided, but not identical in all fishes. No fish has a neck, or any limb, or testicles anywhere internally or externally and no breasts. Fish have two peculiarities, gills and fins: they first take in water through the mouth and then expel it through the gills: most fishes have four fins, though the elongated ones, such as the eel, have only two, and these are situated near the gills. Similarly the various species of gray mullet have two; so has the tape-fish. Some of the elongated fishes have no fins at all, e.g., the muraena, and their gills are not well articulated like those of other fishes. Of those which have gills, some have coverings on them, though none of the Selachia has any such covering. All which have this covering have their gills placed at the side; whereas among selachia the broad ones have them down below the ventral surface (examples are the torpedo fish and the ray); the elongated ones have them on the sides (examples are all the dogfish). The fishing-frog has them placed at the side, and covered, not with a spiny covering as in the non-selachians, but with a covering consisting of skin. Fishes differ from other animals otherwise than in possessing gills. Unlike viviparous land animals they have no hair, and unlike some of the oviparous quadrupeds they have no horny scales, and unlike birds they have no feathers. Generally they are covered with ordinary scales, though a few are rough skinned, and a very small number are smooth-skinned; to the smooth skinned also belong the conger, the eel, and the tunny. Organs of sensation. Fishes have none of these, at least none observable, except eyes-neither the organ itself nor corresponding passages for hearing or smell. But they all have eyes, without eyelashes, though their eyes are not hard. The whole tribe of fishes is blooded. Some are viviparous: the scaly ones are oviparous; all the selachia, except the fishing frog, are viviparous.
Aristotle’s (Greek philosopher and scientist) definition in “Historia Animalium” 340 BC: To begin with, fishes have a head, dorsal and ventral sides; in the last named situation are placed the belly and viscera; and at the rear fishes have a tail which is continuous and undivided, but not identical in all fishes. No fish has a neck, or any limb, or testicles anywhere internally or externally and no breasts. Fish have two peculiarities, gills and fins: they first take in water through the mouth and then expel it through the gills: most fishes have four fins, though the elongated ones, such as the eel, have only two, and these are situated near the gills. Similarly the various species of gray mullet have two; so has the tape-fish. Some of the elongated fishes have no fins at all, e.g., the muraena, and their gills are not well articulated like those of other fishes. Of those which have gills, some have coverings on them, though none of the Selachia has any such covering. All which have this covering have their gills placed at the side; whereas among selachia the broad ones have them down below the ventral surface (examples are the torpedo fish and the ray); the elongated ones have them on the sides (examples are all the dogfish). The fishing-frog has them placed at the side, and covered, not with a spiny covering as in the non-selachians, but with a covering consisting of skin. Fishes differ from other animals otherwise than in possessing gills. Unlike viviparous land animals they have no hair, and unlike some of the oviparous quadrupeds they have no horny scales, and unlike birds they have no feathers. Generally they are covered with ordinary scales, though a few are rough skinned, and a very small number are smooth-skinned; to the smooth skinned also belong the conger, the eel, and the tunny. Organs of sensation. Fishes have none of these, at least none observable, except eyes-neither the organ itself nor corresponding passages for hearing or smell. But they all have eyes, without eyelashes, though their eyes are not hard. The whole tribe of fishes is blooded. Some are viviparous: the scaly ones are oviparous; all the selachia, except the fishing frog, are viviparous.
