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The unipapillary kidney with a single renal pyramid is the simplest type of kidney in mammals, from which the more structurally complex kidneys are believed to have evolved. [17] [6] [18] Differences in kidney structure are the result of adaptations during evolution to variations in body mass and habitats (in particular, aridity) between species.
A polyp is an animal of very simple structure, [1] a living fossil that has not changed significantly for about half a billion years (per generally accepted dating of Cambrian sedimentary rock). [citation needed] The external form of the polyp varies greatly in different cases.
In order to differentiate the use of the word mesenchyme in vertebrate embryology (that is, undifferentiated tissue found in embryonic true [ento-]mesoderm from which are derived all connective tissues, blood vessels, blood cells, the lymphatic system, and the heart) and the use in invertebrate zoology (a more-or-less solid but loosely organized tissue consisting of a gel matrix [the mesoglea ...
The kidney of the frog is an opisthonephros. The kidneys are seen as two elongated, red organs in this image. The opisthonephros is the functional adult kidney in lampreys (cyclostomes), most fishes, and amphibians. [1] It is formed from the extended mesonephros along with tubules from the posterior nephric ridge. [2]
The reniculate kidney is a multilobed kidney found in marine and aquatic mammals such as pinnipeds (seals, sea lions and walruses) and cetaceans (dolphins and whales) but absent in terrestrial mammals except bears. [1] Kidneys of this morphology have increased surface area for removing toxins from the body more efficiently than a non-lobed kidney.
Some animals, like cnidarians, produce two germ layers (the ectoderm and endoderm) making them diploblastic. Other animals such as bilaterians produce a third layer (the mesoderm) between these two layers, making them triploblastic. Germ layers eventually give rise to all of an animal's tissues and organs through the process of organogenesis.
As octocorals, sea pens are colonial animals with multiple polyps (which look somewhat like miniature sea anemones), each with eight tentacles. Unlike other octocorals, however, a sea pen's polyps are specialized to specific functions: a single polyp develops into a rigid, erect stalk (the rachis ) and loses its tentacles, forming a bulbous ...
Cnidarians are the simplest animals in which the cells are organised into tissues. [33] The starlet sea anemone is used as a model organism in research. [34] It is easy to care for in the laboratory and a protocol has been developed which can yield large numbers of embryos on a daily basis. [35]