Sedentary Animal

Sedentary Animal

 

any one of the mostly marine bottom-dwelling animals attached to a substrate as adults. Sedentary animals include many protozoans, for example, some foraminifers, heliozoans, and infusorians (including vorticellae and stentors). Also sedentary are scyphozoans, sponges, hydroids, and coral polyps—many of them living in the tubes of polychaetous worms. Other sedentary animals are barnacles, some bivalve mollusks (for example, oysters and tridacnas), all bryozoans, brachiopods, phoronids, pterygobranchiates, pogonoforans, stalked crinoids, and ascidians.

Many sedentary animals are colonial forms, but solitary species frequently form large masses. Adaptations to a sedentary mode of life characteristic of many of these animals include the presence of a solid calcareous skeleton, hermaphroditism, increased fecundity, and the presence of tentacles to trap prey or devices to filter food particles from the water (sediment feeders). The transition to the sedentary mode of life frequently led in the course of evolution to a simplification of organization and to the origin of radial symmetry. Attachment to other animals may be the initial stage of transition to parasitism.

Sometimes included among sedentary animals are certain almost motionless, animals that are not attached to a substrate, for example, Mya mollusks, which pass their entire lives in a single hole, and some burrowing animals.

G. M. BELIAEV

References in periodicals archive ?
The mice that ran weighed 30% less than the sedentary animals after the five-week exercise period.
Sedentary animals were placed in the swimming tank for 1 min in the same period of exercise training protocol to mimic the water stress with the experimental protocol.
The morphologic renal analysis employed in our study revealed that the sclerotic glomeruli were more preserved in trained SHR compared to sedentary animals of the same lineage.
The collateral vessels themselves were larger and less prone to constriction - a problem exacerbated with PAD - than in sedentary animals.
Muscle weight was examined between the different groups; however, absolute weight was higher in sedentary animals, irrespective of the diet.
On the other hand, a lower plasma FFA level was observed in trained rats (Sup/Ex and Ctrl/Ex) compared to sedentary animals (Sup/Sed and Ctrl/Sed).
The collateral vessels themselves were larger and less prone to constriction, which is a problem exacerbated with PAD, than in sedentary animals.
In the present study, the sedentary animals may have reached their maximum capacity of intramuscular Cr storage, and excessive Cr may have been capitates by renal and hepatic tissue causing some lesion.
However, the CAT activity of trained and sedentary animals tended to decrease during protocol, only a decreased activity of CAT in 36-week trained reach to significance as compared with their corresponding 12-week groups (p < 0.