Question

3. Feats of animal navigation are often compelling because they use sensory systems that we are unfamiliar with. Pick an example of an animal that uses a sensory mode that we do not rely on and describe its mechanism of navigation.

4. Animals may choose habitats for a variety of reasons. Discuss the reasons for habitat selection and how we can understand this decision.

Answer 1

3. Pit vipers use a remarkable mechanism of sensing infrared radiation or heat waves as a part of detecting warm blooded animals or prey like rats. The structures that help Pit vipers to detect heat changes is called the Pits, located between the eye and the nostril just 0.5 cm deep. Pits have a membranous structure that have around 7000 nerve endings. It can detect minute temperature differences from a distance of 40 metres. How are the neurons present in the pit activated based on the infrared radiation? The nerve endings in the pit have heat sensitive sodium channels that opens when the pit is even slightly warm, hence triggering a nerve impulse. A warm blooded animal like rats keep the body temperature constant irrespective of the temperature fluctuation of the environment. When the environment temperature drops at night and the body temperature of rats are still high, pit vipers can navigate and hunt rats, because of the temperature difference.

4. Reasons for habitat selection- Living organisms select a particular habitat for two basic reasons survival and to reproduce.

A. Availability of Food, water, and Area- Food is the basic need of any animal to survive. So based on the availability of food and water resources animals choose their habitat. The area in which they live also plays an important role. The area determines the density of the population. The requirement of different animals for food and water is different, and these difference makes some species habitat specialists and some as generalists.  These cues are used by an animal to select a particular habitat.

B. Environmental Change- When the environment is not favourable because of sessional variation of temperature for example, animals migrate temporarily or change the habitat temporarily.

C. Competition- habitat selection by an animal can also be based on competition for food and mate. When individuals of the same species compete for the same food or same resources (Intraspecific competition), or when individuals from other species compete for the same resources (Interpsecific competition). Animals choose the habitat where both intra and interspecific competitions are less.

D. Predators- Animals try to avoid predators. So they choose a habitat where the predator population is less.