The problems of survival of animals on land are very different from those of survival of animals in aquatic environment. Describe four problems associated with animal survival in terrestrial environments but not in aquatic environments. For each problem, explain a physiological of structural solution.
Four problems faced by animals on land are breathing (respiration)
Because of these three extraembryonic membranes, oviparous reptiles were able and, indeed, forced, to lay their eggs on land. The young hatch fully formed, without a larval stage, ready to seek their own food. Not only were reptiles liberated from returning to water to lay their eggs; aquatic oviparous species must go onto land to do so, since porous eggs would become water-logged in an aqueous environment.
Reptiles exhibit other adaptations to terrestrial life. The body surface is covered with a thick layer of cornified epidermal cells that is organized into plaques, shields, or surface scales unlike the bony dermal scales of fishes and early amphibians. The scales are impervious to water, which results in water conservation, a necessity for animals living in air and often remote from water. Reptiles have developed a neck by specialization of several postcranial vertebrae. This modification combined with their single occipital condyle, enables reptiles to scan the horizon. The pelvic girdle now articulates with two sacral vertebrae, providing a stouter brace for more powerful hind limbs. The digits are supplied with claws, and a new kidney, the metanephros, has come into existence as a modification of the amphibian kidney. The heart is partially or completely divided into right and left chambers, thereby separating the systemic and pulmonary circulations to an extent not achieved in anamniotes.
These then are the reptiles: scaly, clawed, mostly terrestrial tetrapods lacking feathers and hair, which, excepting viviparous species, lay macrolecithal, shell-covered (cleidoic) eggs on land, the embryos of which develop within an amnion, and the young of which are hatched fully formed. We will look briefly at the five subclasses, Anapsida, Lepidosauria, Archosauria, Euryapsida, and Synapsida, which have been erected according to the number of temporal arches and fossae in the skull.
From: RICHA CHAWLA <reshma_221986@
To: mho <mumbaihangout@
Cc: boon119@gmail.
Sent: Monday, December 22, 2008 1:15:25 PM
Subject: :|: MHO :|: hi
| hi boon, nd my group members, actually meine bahut baar is group par mail ki bt mujhe kabhi koi response nhi mila so aaj dubara mujhe help chahiye isliye likh rhi hoon actually i wanna know abt (TERRESTRIAL ADAPTATION IN REPTILES) actually meine yahoo or google par bhi seacrh kiya bt mujhe kuch samajh nhi aa rha so pls.. agar koi meri help kr ske. i should be very thankfull to all of you. Thanks & Regards Richa |
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