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Advances in confocal microscopy technology led to the discovery of embryonic cleavage patterns, which differs between the annelids and arthropods. [5] Annelids show spiral cleavage, meaning that each embryonic cleavage occurs at progressive 90-degree angles with respect to the animal–vegetal axis. Arthropods, on the other hand, display a ...
English: This diagram is showing the difference of the two major types of coelomates: the protostomes (molluscs, annelids, arthropods, ...) and deuterostomes (echinoderms, vertebrates, ...). These groups differ in several characteristics of early development; In deuterostomes blastula divisions is called " radial cleavage " because it occurs ...
Annelids are members of the protostomes, one of the two major superphyla of bilaterian animals – the other is the deuterostomes, which includes vertebrates. [68] Within the protostomes, annelids used to be grouped with arthropods under the super-group Articulata ("jointed animals"), as segmentation is obvious in most members of both phyla ...
Dunn et al. in 2008 suggested that the tardigrada could be grouped along with the nematodes, leaving Onychophora as the sister group to the arthropods. [11] The non-panarthropod members of Ecdysozoa have been grouped as Cycloneuralia but they are more usually considered paraphyletic in representing the primitive condition from which the ...
The Spiralia are a morphologically diverse clade of protostome animals, including within their number the molluscs, annelids, platyhelminths and other taxa. [4] The term Spiralia is applied to those phyla that exhibit canonical spiral cleavage, a pattern of early development found in most (but not all) members of the Lophotrochozoa. [5]
List of annelid families describes the taxa relationships in the phylum Annelida, which contains more than 17,000 extant species including ragworms, earthworms, and leeches. [ 1 ] Class Polychaeta
[1] [2] Well-known examples of protostomes are arthropods, molluscs, annelids, flatworms and nematodes. They are also called schizocoelomates since schizocoely typically occurs in them. Together with the Deuterostomia and Xenacoelomorpha, these form the clade Bilateria, animals with bilateral symmetry, anteroposterior axis and three germ layers ...
Marine arthropods range in size from the microscopic crustacean Stygotantulus to the Japanese spider crab. Arthropods' primary internal cavity is a hemocoel, which accommodates their internal organs, and through which their haemolymph - analogue of blood - circulates; they have open circulatory systems. Like their exteriors, the internal organs ...