Animal | Definition, Types, & Facts | Britannica
4 天之前 · animal, (kingdom Animalia), any of a group of multicellular eukaryotic organisms (i.e., as distinct from bacteria, their deoxyribonucleic acid, or DNA, is contained in a membrane-bound nucleus). They are thought to have evolved independently from the unicellular eukaryotes.
Characteristics of animals | Britannica
animal, Any member of the kingdom Animalia (see taxonomy), a group of many-celled organisms that differ from members of the two other many-celled kingdoms, the plants and the fungi (see fungus), in several ways.
Animal - Multicellular, Heterotrophic, Eukaryotes | Britannica
2024年12月13日 · Animal - Multicellular, Heterotrophic, Eukaryotes: A characteristic of members of the animal kingdom is the presence of muscles and the mobility they afford. The muscles that distinguish animals from plants or fungi are specializations of the actin and myosin microfilaments common to all eukaryotic cells.
animal - Students | Britannica Kids | Homework Help
All members of the animal kingdom (Animalia) are multicellular—that is, all have bodies composed of many cells. Multicellular animals are sometimes referred to as metazoans, to distinguish them from the protozoans—single-celled organisms that once were classified as animals and later grouped in the kingdom Protista. The simplest animals ...
Insect | Definition, Characteristics, Types, Beneficial, Pest ...
2024年12月7日 · Insect, any member of the class Insecta, the largest class of phylum Arthropoda. Insects have segmented bodies, jointed legs, and exoskeletons. They are distinguished from other arthropods by their body, which has three major regions: the head, the three-segmented thorax, and the many-segmented abdomen.
Animal Kingdom Kids - Britannica Kids
Amphibians and reptiles are two groups of animals that share certain features. They are vertebrates, meaning that they have a backbone, and they are cold-blooded. Being cold-blooded means that they rely on outside sources to keep them warm. They …
Plant - Photosynthesis, Reproduction, Evolution | Britannica
2024年11月18日 · The kingdom Plantae includes organisms that range in size from tiny mosses to giant trees. Despite this enormous variation, all plants are multicellular and eukaryotic (i.e., each cell possesses a membrane-bound nucleus that contains the chromosomes).
Chordate | Definition, Characteristics, & Facts | Britannica
2024年10月22日 · External features. An ancestral chordate, as suggested by the adult lancelet and the tadpole larva of tunicates, had a distinct front and hind end, an anterior mouth, a posterior tail above an anus, unpaired fins, and gill slits that opened directly to the exterior.
Sponge | Definition, Features, Reproduction, & Facts | Britannica
2024年11月5日 · In structure, function, and development, sponges are distinct from other animals; one of their most noticeable features is that they lack organs. Many zoologists have regarded sponges as occupying an isolated position in the animal kingdom and classify them in the subkingdom Parazoa; however, molecular data suggest that both sponges and more ...
Vertebrate | Definition, Characteristics, Examples, Classification ...
2024年11月18日 · General features. Although the vertebral column is perhaps the most obvious vertebrate feature, it was not present in the first vertebrates, which probably had only a notochord. The vertebrate has a distinct head, with a differentiated tubular brain and three pairs of sense organs (nasal, optic, and otic).