Xenoturbella has no brain: is it true ?
Xenoturbella has no brain: is it true ?
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Xenoturbella is a genus of bilaterian animals; it contains two marine worm-like species. The first known species (Xenoturbella bocki) was discovered in 1915 by Sixten Bock but the first published description was only in 1949 by Einar Westblad.
Xenoturbella has a very simple body plan: it has no brain, no through gut, no excretory system, no organized gonads (but does havegametes; eggs and embryos occur in follicles [Israelsson and Budd]), or any other defined organs except for a statocyst containing flagellated cells; it has cilia and a diffuse nervous system. The animal is up to 4 centimetres (1.6 in) long, and has been found off the coasts of Sweden, Scotland and Iceland.
Eggs of Xenoturbella are 0.2 mm wide, pale orange and opaque. Newly hatched embryos are free-swimming (tending to stay close to water surface) and ciliated. They feature no mouth and they do not apparently feed. They are similar to the larvae of acoelomate Neochildia fusca.....Source
Xenoturbella has a very simple body plan: it has no brain, no through gut, no excretory system, no organized gonads (but does havegametes; eggs and embryos occur in follicles [Israelsson and Budd]), or any other defined organs except for a statocyst containing flagellated cells; it has cilia and a diffuse nervous system. The animal is up to 4 centimetres (1.6 in) long, and has been found off the coasts of Sweden, Scotland and Iceland.
Eggs of Xenoturbella are 0.2 mm wide, pale orange and opaque. Newly hatched embryos are free-swimming (tending to stay close to water surface) and ciliated. They feature no mouth and they do not apparently feed. They are similar to the larvae of acoelomate Neochildia fusca.....Source
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