The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus.The GI tract contains all the major organs of the digestive system, in humans and other animals, including the esophagus, stomach, and intestines.Food taken in through the mouth is digested to extract nutrients and absorb …

The fertilized eggs develop into larvae by dividing until there are enough cells to form a hollow sphere and then a depression forms at one end and eventually becomes the digestive cavity. However, in Cnidarians, the depression formed at the end is from the yolk, while in bilaterians it forms at the other end.

A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision.It is the most complex organ in a vertebrate's body. In a human, the cerebral cortex contains approximately 14–16 billion neurons, and the estimated number of neurons in the …

Symmetry in biology refers to the symmetry observed in organisms, including plants, animals, fungi, and bacteria. External symmetry can be easily seen by just looking at an organism. ... The bilateral symmetry of bilaterians is a complex trait which develops due to the expression of many genes. The bilateria have two axes of polarity.

Embryology (from Greek ἔμβρυον, embryon, "the unborn, embryo"; and -λογία, -logia) is the branch of animal biology that studies the prenatal development of gametes (sex cells), fertilization, and development of embryos and fetuses.Additionally, embryology encompasses the study of congenital disorders that occur before birth, known as teratology.

The name echinoderm is from Ancient Greek ἐχῖνος (ekhînos) 'hedgehog', and δέρμα (dérma) 'skin'. Echinoderms are bilaterians, meaning that their ancestors were mirror-symmetric.Among the bilaterians, they belong to the deuterostome division, meaning that the blastopore, the first opening to form during embryo development, becomes the anus instead of the mouth.

Marine invertebrates are the invertebrates that live in marine habitats.Invertebrate is a blanket term that includes all animals apart from the vertebrate members of the chordate phylum. Invertebrates lack a vertebral column, and some have evolved a shell or a hard exoskeleton.As on land and in the air, marine invertebrates have a large variety of body plans, and have been …

Hewan, binatang, fauna, margasatwa, atau satwa adalah organisme eukariotik multiseluler yang membentuk kerajaan biologi Animalia. Dengan sedikit pengecualian, hewan mengonsumsi bahan organik, menghirup oksigen, dapat bergerak, bereproduksi secara seksual, dan tumbuh dari bola sel yang berongga, blastula, selama fase perkembangan embrio.Lebih dari 1,5 juta spesies …

May 08, 2004 · 動物，或稱後生動物（ Metazoan ），是一群多細胞 真核生物，在生物分類學上構成名為動物界（學名： Animalia ）的分類階層。 除了少數特例外，絕大多數動物會消耗有機物質，呼吸氧氣，能夠移動和有性生殖，其胚胎發育過程從空心細胞球（囊胚）開始。 目前已有逾150萬個現生動物物種被發表 ...

Ctenophora (/ t ə ˈ n ɒ f ər ə /; sg. ctenophore / ˈ t ɛ n ə f ɔːr, ˈ t iː n ə-/; from Ancient Greek κτείς (kteis) 'comb', and φέρω (pherō) 'to carry') comprise a phylum of marine invertebrates, commonly known as comb jellies, that inhabit sea waters worldwide. They are notable for the groups of cilia they use for swimming (commonly referred to as "combs"), and they are ...