Reptile vs. Fish

Main Difference

The main difference between Reptile and Fish is that the Reptile is a class of animals and Fish is a vertebrate animal that lives in water and (typically) has gills

• Reptile

  Reptiles are tetrapod animals in the class Reptilia, comprising today’s turtles, crocodilians, snakes, amphisbaenians, lizards, tuatara, and their extinct relatives. The study of these traditional reptile orders, historically combined with that of modern amphibians, is called herpetology.

  Because some reptiles are more closely related to birds than they are to other reptiles (e.g., crocodiles are more closely related to birds than they are to lizards), the traditional groups of “reptiles” listed above do not together constitute a monophyletic grouping or clade (consisting of all descendants of a common ancestor). For this reason, many modern scientists prefer to consider the birds part of Reptilia as well, thereby making Reptilia a monophyletic class, including all living Diapsids. The term “reptiles” is sometimes used as shorthand for ‘non-avian Reptilia’.The earliest known proto-reptiles originated around 312 million years ago during the Carboniferous period, having evolved from advanced reptiliomorph tetrapods that became increasingly adapted to life on dry land. Some early examples include the lizard-like Hylonomus and Casineria. In addition to the living reptiles, there are many diverse groups that are now extinct, in some cases due to mass extinction events. In particular, the Cretaceous–Paleogene extinction event wiped out the pterosaurs, plesiosaurs, ornithischians, and sauropods, alongside many species of theropods, many crocodyliforms, and many squamates (e.g. mosasaurs).

  Modern non-avian reptiles inhabit all the continents except Antarctica, although some birds are found on the periphery of Antarctica. Several living subgroups are recognized: Testudines (turtles and tortoises), 350 species; Rhynchocephalia (tuatara from New Zealand), 1 species; Squamata (lizards, snakes, and worm lizards), over 10,200 species; and Crocodilia (crocodiles, gharials, caimans, and alligators), 24 species.Reptiles are tetrapod vertebrates, creatures that either have four limbs or, like snakes, are descended from four-limbed ancestors. Unlike amphibians, reptiles do not have an aquatic larval stage. Most reptiles are oviparous, although several species of squamates are viviparous, as were some extinct aquatic clades – the fetus develops within the mother, contained in a placenta rather than an eggshell. As amniotes, reptile eggs are surrounded by membranes for protection and transport, which adapt them to reproduction on dry land. Many of the viviparous species feed their fetuses through various forms of placenta analogous to those of mammals, with some providing initial care for their hatchlings. Extant reptiles range in size from a tiny gecko, Sphaerodactylus ariasae, which can grow up to 17 mm (0.7 in) to the saltwater crocodile, Crocodylus porosus, which can reach 6 m (19.7 ft) in length and weigh over 1,000 kg (2,200 lb).

• Fish

  Fish are gill-bearing aquatic craniate animals that lack limbs with digits. They form a sister group to the tunicates, together forming the olfactores. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Tetrapods emerged within lobe-finned fishes, so cladistically they are fish as well. However, traditionally fish are rendered paraphyletic by excluding the tetrapods (i.e., the amphibians, reptiles, birds and mammals which all descended from within the same ancestry). Because in this manner the term “fish” is defined negatively as a paraphyletic group, it is not considered a formal taxonomic grouping in systematic biology, unless it is used in the cladistic sense, including tetrapods. The traditional term pisces (also ichthyes) is considered a typological, but not a phylogenetic classification.

  The earliest organisms that can be classified as fish were soft-bodied chordates that first appeared during the Cambrian period. Although they lacked a true spine, they possessed notochords which allowed them to be more agile than their invertebrate counterparts. Fish would continue to evolve through the Paleozoic era, diversifying into a wide variety of forms. Many fish of the Paleozoic developed external armor that protected them from predators. The first fish with jaws appeared in the Silurian period, after which many (such as sharks) became formidable marine predators rather than just the prey of arthropods.

  Most fish are ectothermic (“cold-blooded”), allowing their body temperatures to vary as ambient temperatures change, though some of the large active swimmers like white shark and tuna can hold a higher core temperature.Fish can communicate in their underwater environments through the use of acoustic communication. Acoustic communication in fish involves the transmission of acoustic signals from one individual of a species to another. The production of sounds as a means of communication among fish is most often used in the context of feeding, aggression or courtship behaviour. The sounds emitted by fish can vary depending on the species and stimulus involved. They can produce either stridulatory sounds by moving components of the skeletal system, or can produce non-stridulatory sounds by manipulating specialized organs such as the swimbladder.Fish are abundant in most bodies of water. They can be found in nearly all aquatic environments, from high mountain streams (e.g., char and gudgeon) to the abyssal and even hadal depths of the deepest oceans (e.g., gulpers and anglerfish), although no species has yet been documented in the deepest 25% of the ocean. With 33,600 described species, fish exhibit greater species diversity than any other group of vertebrates.Fish are an important resource for humans worldwide, especially as food. Commercial and subsistence fishers hunt fish in wild fisheries (see fishing) or farm them in ponds or in cages in the ocean (see aquaculture). They are also caught by recreational fishers, kept as pets, raised by fishkeepers, and exhibited in public aquaria. Fish have had a role in culture through the ages, serving as deities, religious symbols, and as the subjects of art, books and movies.

• Fish (noun)

  a limbless cold-blooded vertebrate animal with gills and fins living wholly in water

  “the huge lakes are now devoid of fish”

• Fish (noun)

  the flesh of fish as food

  “a dinner of meat, dried fish, and bread”

• Fish (noun)

  the zodiacal sign or constellation Pisces.

• Fish (noun)

  used in names of invertebrate animals living wholly in water, e.g. cuttlefish, shellfish, jellyfish.

• Fish (noun)

  a torpedo.

• Fish (noun)

  a person who is strange in a specified way

  “he is generally thought to be a bit of a cold fish”

• Fish (noun)

  a flat plate that is fixed on a beam or across a joint in order to give additional strength.

• Fish (noun)

  a long, slightly curved piece of wood that is lashed to a ship’s damaged mast or spar as a temporary repair.

• Fish (verb)

  catch or try to catch fish, typically by using a net or hook and line

  “he was fishing for pike”

  “I’ve told the girls we’ve gone fishing”

• Fish (verb)

  catch or try to catch fish in (a particular body of water)

  “many of the lochs we used to fish are now affected by forestry”

• Fish (verb)

  search by groping or feeling for something concealed

  “he fished for his registration certificate and held it up to the policeman’s torch”

• Fish (verb)

  try subtly or deviously to elicit a response or some information from someone

  “I was not fishing for compliments”

• Fish (verb)

  pull or take something out of water or a receptacle

  “the body of a woman had been fished out of the river”

• Fish (verb)

  mend or strengthen with a fish.

• Fish (verb)

  join (rails in a railway track) with a fishplate.