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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.
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 ...
Furthermore, the fivefold symmetry, classical for echinoderms, although preserved structurally, is doubled here by a bilateral symmetry which makes them look like chordates. However, a central symmetry is still visible in some species through five 'radii', which extend from the mouth to the anus (just like for sea urchins), on which the tube ...
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 ...
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]
Nettle jelly. A nerve net consists of interconnected neurons lacking a brain or any form of cephalization.While organisms with bilateral body symmetry are normally associated with a condensation of neurons or, in more advanced forms, a central nervous system, organisms with radial symmetry are associated with nerve nets, and are found in members of the Ctenophora, Cnidaria, and Echinodermata ...
The acorn worms or Enteropneusta are a hemichordate class of invertebrates consisting of one order of the same name. [2] The closest non-hemichordate relatives of the Enteropneusta are the echinoderms. [3] There are 111 known species of acorn worm in the world, [4] the main species for research being Saccoglossus kowalevskii.