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The cause of this posture—often called a "death pose"—has been a matter of scientific debate. Traditional explanations ranged from strong ligaments in the animal's neck desiccating and contracting to draw the body into the pose, [1] to water currents arranging the remains in the position. [2]
As a result, the animals absorb liquid, begin to swell, and separate from the substrate so that they float freely in the water. In the protected interior space, the ventral cells form an ovum surrounded by a special envelope, the fertilisation membrane; the ovum is supplied with nutrients by the surrounding syncytium, allowing energy-rich yolk ...
' flat animals ') [3] is a phylum of free-living (non-parasitic) marine invertebrates. [4] [5] They are blob-like animals composed of aggregations of cells. Moving in water by ciliary motion, eating food by engulfment, reproducing by fission or budding, placozoans are described as "the simplest animals on Earth."
The dugong (/ ˈ d (j) uː ɡ ɒ ŋ /; Dugong dugon) is a marine mammal.It is one of four living species of the order Sirenia, which also includes three species of manatees.It is the only living representative of the once-diverse family Dugongidae; its closest modern relative, Steller's sea cow (Hydrodamalis gigas), was hunted to extinction in the 18th century.
The word "protozoa" (singular protozoon) was coined in 1818 by zoologist Georg August Goldfuss (=Goldfuß), as the Greek equivalent of the German Urthiere, meaning "primitive, or original animals" (ur-'proto-' + Thier 'animal'). [11] Goldfuss created Protozoa as a class containing what he believed to be the simplest animals. [3]
Not much is known about the lifecycle of C. exigua. It exhibits sexual reproduction. The species starts as a juvenile in a short, free-living stage in the water column. [2] Juveniles likely first attach to the gills of a fish and become males. As they mature, they become females, with mating likely occurring on the gills.
Hydra cannot be found in impaired water due to their low tolerance to pollution. They can be used to rank toxicants on level of potential hazard. The simple tubular body and diploblastic membranes, all of the epithelial cells are in constant contact with the environment, this allows for toxic substances being exposed to all body surface. [5]
Tardigrades (/ ˈ t ɑːr d ɪ ɡ r eɪ d z / ⓘ), [1] known colloquially as water bears or moss piglets, [2] are a phylum of eight-legged segmented micro-animals. They were first described by the German zoologist Johann August Ephraim Goeze in 1773, who called them Kleiner Wasserbär ' little water bear ' .