Search results
Results from the WOW.Com Content Network
Echinoderms become sexually mature after approximately two to three years, depending on the species and the environmental conditions. Almost all species have separate male and female sexes, though some are hermaphroditic. The eggs and sperm cells are typically released into open water, where fertilisation takes place.
Echinolampas. This list of prehistoric echinoids is an attempt to create a comprehensive listing of all genera from the fossil record that have ever been considered to be echinoids, excluding purely vernacular terms. The list includes all commonly accepted genera, but also genera that are now considered invalid, doubtful (nomina dubia), or were ...
In these cases, a small number of female gonads were observed within male individuals, typically ranging from 2 to 5 gonads out of a total of 45–50. An extraordinary occurrence of complete sex reversal was documented in B. belcheri, where a female amphioxus raised in laboratory conditions underwent a transformation into a male (Zhang et al ...
A brittle star, Ophionereis reticulata A sea cucumber from Malaysia Starfish exhibit a wide range of colours. This List of echinoderm orders concerns the various classes and orders into which taxonomists categorize the roughly 7000 extant species [1] as well as the extinct species of the exclusively marine phylum Echinodermata.
The name urchin is an old word for hedgehog, which sea urchins resemble; they have archaically been called sea hedgehogs. [6] [7] The name is derived from the Old French herichun, from Latin ericius ('hedgehog'). [8] Like other echinoderms, sea urchin early larvae have bilateral symmetry, [9] but they develop five-fold symmetry as they mature ...
Helicoplacus. Helicoplacus (often misspelled Helioplacus) is the earliest well-studied fossil echinoderm. Fossil plates are known from several regions. Complete specimens were found in Lower Cambrian strata of the White Mountains of California. The animal was a cigar-shaped creature up to 7 centimetres (2.8 in) long that stood upright on one end.
S. List of prehistoric sea cucumbers. List of prehistoric starfish genera. List of prehistoric stylophoran genera. Categories: Prehistoric echinoderms. Lists of prehistoric animals. Lists of echinoderms.
Category. : Echinoderms. Wikimedia Commons has media related to Echinodermata. Echinoderms (sea urchins, sea lilies, sea stars, crinoids, ...) are animals in the phylum Echinodermata. There are 5 subphyla, some of them being extinct: †Homalozoa, Crinozoa, Asterozoa, Echinozoa and †Blastozoa.