Question

Terrestrial animals must
(a) Excrete large amounts of urine
(b) Conserve water
(c) Activity pump out salts through skin
(d) Excrete a large number of salts in the urine

Answer 1

Hint: Terrestrial animals are those animals that live totally on land (e.g., cats, ants, spiders). Aquatic animals are those animals which live predominantly or entirely within the water (e.g., fish, lobsters, octopus).

Complete answer: Since terrestrial animals do not have automatic access to either fresh or saltwater they need to conserve water to manage water content in other ways balancing off gains and losses.
Ammonia is the foremost most harmful form and needs a huge amount of water for its elimination, whereas uric acid, being the least toxic, is often removed with a minimum loss of water. The method of excreting ammonia is Ammonotelism.

Additional information:
1. Aquatic amphibians, many bony fishes and aquatic insects are ammonotelic in nature. 2. Ammonia is quickly soluble, So, it is basically excreted by diffusion over body surfaces or by gill surfaces (in fish) as ammonium ions. 3. Terrestrial adaptation necessitated the assembly of lesser toxic nitrogenous wastes like urea and uric acid for the conservation of water. 4. Many terrestrial amphibians, mammals and marine fishes mainly excrete urea and are called ureotelic animals. 5. Some organisms eliminate nitrogenous wastes as uric acid e.g. birds, land snails, reptiles, and insects that have a minimum loss of water and are called uricotelic animals.
So, the correct answer is ‘Conserve water’.

Note: Many nitrogen-containing substances, ions, carbon dioxide, water, etc., that accumulate within the body need to be eliminated. The environmental nitrogenous wastes formed and their excretion vary among animals, mainly depending on the habitat (availability of water). Ammonia, urea, and acid are the main nitrogenous wastes excreted.