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Fin fish like salmon have gills, are covered in scales, and reproduce by laying eggs. Eels, by contrast, have worm-like bodies and exceedingly slimy skin. Lungfish gulp air.
A fish (pl.: fish or fishes) is an aquatic, anamniotic, gill-bearing vertebrate animal with swimming fins and a hard skull, but lacking limbs with digits.Fish can be grouped into the more basal jawless fish and the more common jawed fish, the latter including all living cartilaginous and bony fish, as well as the extinct placoderms and acanthodians.
- Overview
- Structural diversity
A fish is any of approximately 34,000 species of vertebrate animals. The term fish is applied to a variety of vertebrates of several evolutionary lines. It describes a life-form rather than a taxonomic group.
How do fish sleep?
When a fish sleeps, it exists in a seemingly listless state in which the fish maintains its balance but moves slowly. If attacked or disturbed, most fish can dart away. A few kinds of fish lie on the bottom to sleep. Most fish do not have eyelids, so they cannot close their eyes to sleep.
How do fish hear?
The organs of hearing in fish are entirely internal, located within the skull, on each side of the brain, and somewhat behind the eyes. Sound waves, especially those of low frequencies, travel readily through water and impinge directly upon the bones and fluids of the head and body to be transmitted to the hearing organs.
fish, any of approximately 34,000 species of vertebrate animals (phylum Chordata) found in the fresh and salt waters of the world. Living species range from the primitive jawless lampreys and hagfishes through the cartilaginous sharks, skates, and rays to the abundant and diverse bony fishes. Most fish species are cold-blooded; however, one species, the opah (Lampris guttatus), is warm-blooded.
Fishes have been in existence for more than 450 million years, during which time they have evolved repeatedly to fit into almost every conceivable type of aquatic habitat. In a sense, land vertebrates are simply highly modified fishes: when fishes colonized the land habitat, they became tetrapod (four-legged) land vertebrates. The popular conception of a fish as a slippery, streamlined aquatic animal that possesses fins and breathes by gills applies to many fishes, but far more fishes deviate from that conception than conform to it. For example, the body is elongate in many forms and greatly shortened in others; the body is flattened in some (principally in bottom-dwelling fishes) and laterally compressed in many others; the fins may be elaborately extended, forming intricate shapes, or they may be reduced or even lost; and the positions of the mouth, eyes, nostrils, and gill openings vary widely. Air breathers have appeared in several evolutionary lines.
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Many fishes are cryptically coloured and shaped, closely matching their respective environments; others are among the most brilliantly coloured of all organisms, with a wide range of hues, often of striking intensity, on a single individual. The brilliance of pigments may be enhanced by the surface structure of the fish, so that it almost seems to glow. A number of unrelated fishes have actual light-producing organs. Many fishes are able to alter their coloration—some for the purpose of camouflage, others for the enhancement of behavioral signals.
Fish are vertebrates (vertebrates have backbones) that live in water. They breathe using special organs called gills.
Jan 3, 2023 · Fish are aquatic vertebrates. They usually have gills, paired fins, a long body covered with scales, and tend to be cold-blooded. “Fish” is a term used to refer to lampreys, sharks, coelacanths, and ray-finned fishes, but is not a taxonomic group, which is a clade or group containing a common ancestor and all its descendants. […]
- What are the 3 types of fish?Bony fish, jawless fish and cartilaginous fish.
- What's the most famous fish?The most famous fish is the coelacanth, which has four lobed fins resembling limbs. It is one of the world’s most ancient fish species. Its name me...
- Can fish feel pain?Yes, fish can feel pain, but it is different from the expression of pain from humans. It is difficult to test fish for pain except by looking for u...
- What do fish eat?Fish can be predatory, foraging or filter-feeding. Their diets can be carnivorous or omnivorous depending on the species and can include prey from...
- How do fish breathe?Fish usually breathe through gills, which filters oxygen through water. However, some fish breathe using different means. Lungfish have lungs and m...
- What are the smallest and largest fish?The smallest fish is the cyprinid fish (8mm) and the largest fish is the whale shark (12m).
- What is the difference between "fish" and "fishes"?“Fish” refers to the singular and one species or to the plural within context. “Fishes” refers to the plural, especially when talking about more th...
- What are the main differences between the flying fox fish and the Siamese algae eater?The main differences between the flying fox fish and the Siamese algae eater are color, length and shape, mouth shape, and algae preferences.
Jul 28, 2022 · The world’s biggest fish is the whale shark, which has a maximum recorded length of 18.8 m / 61.7 ft. The second-largest fish is the basking shark, which has a maximum recorded length of 12.27 m / 40.3 ft. Unlike most sharks, which are active hunters, both the whale shark and the basking shark are filter feeders.
Freshwater makes up less than 3 percent of Earth’s water supply but almost half of all fish species live in rivers, lakes, ponds, and wetlands.
