The Neopteran Questions for an Exam - Essay Example

For instance, the naiad mayflies may live up to one or two years in freshwater aquifers, but adults stages last for a few days at most. Though juvenile mayflies feed on algae and smaller insects, the adults cannot eat due to reduced, non-functional mouthparts. Male fore legs are modified for grasping the female during mating. Near adulthood, naiads rise to the surface of water and molt to develop external wings so that they can move to shore. Mayflies are the only insects which molt after developing functional wings during the pre-adult stage called sub-imago.

Adult mayflies rise on same days forming large flying swarms so that females can lay eggs on water surface before dying. Within the mayflies, different species occupy very different niches. The naiads of Blue Quill mayflies possess large mandibles for grazing detritus and periphyton. Like ephemeroptera, the Odonates also have aquatic naiads but possess a highly modified labium for catching prey. They adults too have chewing mouth parts and hinged jaws are used as tools to capture and bring prey to mouth.

They also have very specialized copulatory behavior in which male grabs female from behind her head with claspers at tip of abdomen, the female receives sperm from his second abdominal segment, and releases fertilized eggs into the water. Males defending the best grazing area have a better chance to attract more females and thus produce more offspring. The neopteran (new wings) insects have the ability to fold their wings back against their abdomen at rest. Neoptera are subdivided into exopterygota and endoterygota depending on the development of wings through the juvenile stages, and into further groups depending on the modification of their mouthparts.

In exopterygota, the metamorphosis is simple or incomplete, and wings gradually develop externally without going through a true pupal stage via molting. The juveniles also usually have similar feeding habits as the adults. The endopterygota undergo complete metamorphosis and development of major structural differences between immature and adult stages occurs. The developing wings are not visible in the initial stages (larvae). An inactive stage called pupa is formed after several molts which does not feed and move.

During this pupal stage big changes take place internally. After the pupal stage, a highly active winged adult appears. The larvae and the adults often adapt to different habitat and use different types of food resources. The evolutionary stages of endopterygota allow the juvenile and adult stages of insects to specialize in different resources, contributing to the extensive and successful radiation of the group. For instance, a bark beetle undergoes egg, the three larval instars, and the pupal stages before rising as an adult beetle.

Question Two The sea otter is the smallest marine mammal having no insulating layer of blubber. The warm skin of sea otter is protected against the cold water by a thick layer of air trapped within very dense and longer fur hairs. The hairs are even denser at back of the body which is mostly in contact with the water. Though air provides far better insulation than blubber, sea otters cannot dive deeper and thus are restricted to shallower, coastal habitats. As Allen rule suggests, the legs, ears, and snout of sea otter are shorter for conserving heat in the colder climate.

They form a streamlined