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New larvae can develop from the preoral hood (a mound like structure above the mouth), the side body wall, the postero-lateral arms, or their rear ends. [67] [68] [69] Cloning is costly to the larva both in resources and in development time. Larvae undergo this process when food is plentiful [70] or temperature conditions are optimal. [69]
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 ]
The name dipleurula, two-sided, was given to stress the fact that the larva of the typically five-rayed, (approximately) radially symmetric adults show a bilateral structure. It was this bilateral structure of the larvae that identified echinoderms as bilaterian animals. The original doliolaria schema shows a benthic, crawling, larva. However ...
Like other echinoderms, crinoids possess a water vascular system that maintains hydraulic pressure in the tube feet. This is not connected to external sea water via a madreporite, as in other echinoderms, but only connected through a large number of pores to the coelom (body cavity). The main fluid reservoir is the muscular-walled ring canal ...
The larvae of the polar sea urchin Sterechinus neumayeri have been found to use energy in metabolic processes twenty-five times more efficiently than do most other organisms. [46] Despite their presence in nearly all the marine ecosystems, most species are found on temperate and tropical coasts, between the surface and some tens of meters deep ...
What they look like: Chiggers, a type of small mite, typically leave clusters of bites that are often very itchy. In many cases, chigger bites appear as small, red and itchy bumps. Sometimes, they ...
Brittle stars, serpent stars, or ophiuroids (from Latin ophiurus ' brittle star '; from Ancient Greek ὄφις (óphis) ' serpent ' and οὐρά (ourá) ' tail '; referring to the serpent-like arms of the brittle star) are echinoderms in the class Ophiuroidea, closely related to starfish.
Do you know what chigger bites look like? The tiny mites may leave behind small, itchy red bumps around your ankles that can be easily confused for other types of insect bites. "They tend to be in ...