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A chordate (/ ˈkɔːrdeɪt / KOR-dayt) is a deuterostomic bilaterial animal belonging to the phylum Chordata (/ kɔːrˈdeɪtə / kor-DAY-tə). All chordates possess, at some point during their larval or adult stages, five distinctive physical characteristics (synapomorphies) that distinguish them from other taxa.
Hemichordate. Acorn worm, a hemichordate. Hemichordata (/ ˌhɛmɪkɔːrˈdeɪtə / HEM-ih-kor-DAY-tə) is a phylum which consists of triploblastic, eucoelomate, and bilaterally symmetrical marine deuterostome animals, generally considered the sister group of the echinoderms.
Earthworms are a classic example of biological homonymous metamery – the property of repeating body segments with distinct regions. In biology, metamerism is the phenomenon of having a linear series of body segments fundamentally similar in structure, though not all such structures are entirely alike in any single life form because some of them perform special functions. [1]
Bilateria (/ ˌ b aɪ l ə ˈ t ɪər i ə / BY-lə-TEER-ee-ə) [2] is a large clade or infrakingdom of animals called bilaterians (/ ˌ b aɪ l ə ˈ t ɪər i ə n / BY-lə-TEER-ee-ən), [3] characterized by bilateral symmetry (i.e. having a left and a right side that are mirror images of each other) during embryonic development.
An unusual feature of sea urchin development is the replacement of the larva's bilateral symmetry by the adult's broadly fivefold symmetry. During cleavage, mesoderm and small micromeres are specified. At the end of gastrulation, cells of these two types form coelomic pouches. In the larval stages, the adult rudiment grows from the left ...
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. For example, the face of a human being has a plane of symmetry down its centre, or a pine cone displays a clear symmetrical spiral pattern.
Cambroernida †. Deuterostomes (from Greek: lit. 'mouth second') are bilaterian animals of the superphylum Deuterostomia (/ ˌdjuːtərəˈstoʊmi.ə /), [3][4] typically characterized by their anus forming before the mouth during embryonic development. Deuterostomia is further divided into four phyla: Chordata, Echinodermata, Hemichordata ...
Dipleurula is a hypothetical larva of the ancestral echinoderm. It represents the type of basis of all larval forms of, at least, the eleutherozoans (all echinoderms except crinoids), where the starfish, sea urchins, sea cucumbers and brittle stars belong. The dipleurula is a bilaterally symmetrical, ciliated echinoderm larva (cilia devoted to ...