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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.
This ancestral organism adopted an attached mode of life with suspension feeding, and developed radial symmetry. Even so, the larvae of all echinoderms are bilaterally symmetrical, and all develop radial symmetry at metamorphosis. Like their ancestor, the starfish and crinoids still attach themselves to the seabed while changing to their adult ...
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.
Overview. Sea cucumber : a -Tentacles, b - Cloaca, c - Ambulacral feet on the ventral side, d -Papillae on the back. Most sea cucumbers have a soft and cylindrical body, rounded off and occasionally fat in the extremities, and generally without solid appendages. Their shape ranges from almost spherical for "sea apples" (genus Pseudocolochirus ...
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.
A tunicate is an exclusively marine invertebrate animal, a member of the subphylum Tunicata (/ ˌtjuːnɪˈkeɪtə / TEW-nih-KAY-tə). This grouping is part of the Chordata, a phylum which includes all animals with dorsal nerve cords and notochords (including vertebrates). The subphylum was at one time called Urochordata, and the term ...
The larvae of echinoderms have bilateral symmetry, but during metamorphosis this is replaced with radial symmetry, typically pentameric. [12] Adult echinoderms are characterized by having a water vascular system with external tube feet and a calcareous endoskeleton consisting of ossicles connected by a mesh of collagen fibres. [ 95 ]
Feeding and digestive system. Lancelets are passive filter feeders, [14] spending most of the time half-buried in sand with only their frontal part protruding. [66] They eat a wide variety of small planktonic organisms, such as bacteria, fungi, diatoms, and zooplankton, and they will also take detritus. [67]