Most fish are poikilothermic, but some fish, like tunas and lamind sharks, use special blood vessel networks to keep their body temperature warmer than the surrounding water. If it is warm, their body temperature will be warmer. If it is cold outside, their body temperature will be cold. These kind of animals have historically been called cold-blooded, but that is not completely accurate. Terms and definitions of words used to describe fishĪn animal whose temperature adjusts with the outside temperature. In Exploring Our Fluid Earth, starfish are called sea stars and jellyfish are called jelly medusa to avoid confusion with true fish.
Even though starfish, jellyfish, and crayfish live in the water, they do not have backbones, and they are not true fish. Crayfish are really crustaceans-related to lobsters (see Fig. Jellyfish are cnidarians-related to sea anemones and corals.
For example, starfish are really echinoderms-related to sea urchins and sea cucumbers. With all of this amazing diversity, it is challenging to make a definition that describes all fishes.ĭefining a fish can also be difficult because the word fish is often used to describe things that are not fish. Some fishes are parasites, some are blind, some are venomous, and some can even produce electricity. Fishes have a wide range of diets, including plankton, algae, fish, seals, and turtles. 4.5 B), with thier skeletons showing great variety in size, composition, and structure (Fig. 4.5 A) to the large whale shark Rhincodon typus, which reaches 12 meters (Fig. Fishes live in warm and cold water-from desert pools to under Arctic pack ice.įishes also range in size from very small, like the tiny cyprinid in Indonesia, which grows to a maximum length of 10 mm (Fig. Fishes live down deep and up high-from the deepest depths of the oceans to mountain pools high in the Andes. With so many animals identified as fish, it is not surprising that they come in all shapes and sizes and can be found in a range of habitats. As scientists make new discoveries, it is expected that the number of species of fishes will outnumber other vertebrates even more. Although these numbers change as new species are discovered, new fishes are found more often than other new vertebrates are found. Of the nearly 50,000 species of animals with backbones, approximately 4,500 are mammals, 9,700 are birds, 6,500 are reptiles, 4,000 are amphibians, and 25,000 are fishes.
In fact, there are about as many species of fishes than there are of all other vertebrates combined (Fig. 4.3).ĭefining a fish is difficult because the term fish includes a very wide range of aquatic animals. However, a convict tang together with a moray eel would be 2 fishes (Fig. For example, 1 convict tang is a fish, 2 convict tangs are 2 fish, and a group of 20 convict tangs are still 20 fish (Fig. If you have two fish, it means you have two individual fish that are the same species, but if you have two fishes, it means you have two individual fish of different species. The word fishes refers to multiple species of fish. The word fish is used to refer to an individual fish or to a group of fish of the same species. The word fish is the same whether it is singular or plural-you can talk about one fish or ten fish. Most fish are streamlined in their general body form. Recall that vertebrates are animals with internal backbones. Accessed July 31, 2012.Fish are aquatic vertebrate animals that have gills but lack limbs with digits, like fingers or toes. The Perfect Storm: The History of the Andrea Gail.