Animal cells uniquely possess the cell junctions called tight junctions, gap junctions, and desmosomes. The Bilateria include the protostomes—in which many groups of invertebrates are found, such as nematodes, arthropods, and molluscs—and the deuterostomes, containing both the echinoderms as well as the chordates, the latter containing the vertebrates. By 1809, in his Philosophie Zoologique, Lamarck had created 9 phyla apart from vertebrates (where he still had 4 phyla: mammals, birds, reptiles, and fish) and molluscs, namely cirripedes, annelids, crustaceans, arachnids, insects, worms, radiates, polyps, and infusorians. Binturong. , Some palaeontologists have suggested that animals appeared much earlier than the Cambrian explosion, possibly as early as 1 billion years ago. Some of them are even trained to carry out “jobs”, e.g. 2014-05-26 22:11:08 2014-05-26 22:11:08. All animals are composed of cells, surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins.  The molluscs, the second-largest animal phylum by number of described species, includes snails, clams, and squids, while the annelids are the segmented worms, such as earthworms, lugworms, and leeches. These groups have a reduced coelom, called a pseudocoelom. Over time, they grow into froglets, and soon into adults that live on land and breathe through the lungs.  Unlike plants and algae, which produce their own nutrients animals are heterotrophic, feeding on organic material and digesting it internally. Lineages of arthropods colonised land around the same time as land plants, probably between 510 and 471 million years ago during the Late Cambrian or Early Ordovician. Hutchins, M., Arthur V. Evans, Rosser W. Garrison and Neil Schlager (Eds) (2003) Grzimek's Animal Life Encyclopedia, 2nd edition. Invertebrates don’t have a backbone, while vertebrate animals do possess a backbone. The cells may then be organized into various animal tissues, such as epithelial tissues, c… , Several animal phyla lack bilateral symmetry. The word "animal" comes from the Latin animalis, meaning having breath, having soul or living being. 2. For this activity, identify whether the highlighted animal in each of the given scenario is an amphibian, bird, insect, mammal, or reptile. Animal Science is described as "studying the biology of animals that are under the control of humankind".  Alligator mississippiensis. Thus, conservation efforts are being made globally to save the dwindling number of animals, especially those nearing extinction. The definition of an animal is a member of the kingdom Animalia, and is typically characterized by a multicellular body, specialized sense organs, voluntary movement, responses to factors in the environment and the ability to acquire and digest food.  Among the mammals, cattle, deer, horses, lions, bats, bears, and wolves are the subjects of myths and worship. A wide variety of animals are kept as pets, from invertebrates such as tarantulas and octopuses, insects including praying mantises, reptiles such as snakes and chameleons, and birds including canaries, parakeets, and parrots all finding a place. These names are important because they allow people throughout the world to communicate unambiguously about animal species.  Sponges lack the complex organization found in most other animal phyla; their cells are differentiated, but in most cases not organised into distinct tissues. Answer. The apparent suddenness of the event may however be an artefact of the fossil record, rather than showing that all these animals appeared simultaneously.  Animals occupy virtually all of earth's habitats and microhabitats, including salt water, hydrothermal vents, fresh water, hot springs, swamps, forests, pastures, deserts, air, and the interiors of animals, plants, fungi and rocks. The animal body is composed of several cells performing specific functions as opposed to bacteria and most protiststhat are unicellular. Thus, the extinction of an animal species causes a major impact on the ecosystem. , Some animals are capable of asexual reproduction, which often results in a genetic clone of the parent. , The remaining animals, the great majority—comprising some 29 phyla and over a million species—form a clade, the Bilateria.  Interactions between animals form complex food webs. 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