Thermographic image of a bat using trapped air as insulation.

While other mammals have one-way valves only in their veins to prevent the blood from flowing backwards, bats also have the same mechanism in their arteries.

The finger bones of bats are much more flexible than those of other mammals. One reason is that the cartilage in their fingers lacks calcium and other minerals nearer the tips, increasing their ability to bend without splintering. The cross-section of the finger bone is also flattened instead of circular as is the bone in a human finger, making it even more flexible. The skin on their wing membranes is a lot more elastic and can stretch much more than is usually seen among mammals.

Because their wings are much thinner than those of birds, bats can maneuver more quickly and more precisely than birds. The surface of their wings are also equipped with touch-sensitive receptors on small bumps called Merkel cells, found in most mammals, including humans. But these sensitive areas are different in bats as each bump has a tiny hair in the center,^[11] making it even more sensitive, and allowing the bat to detect and collect information about the air flowing over its wings. An additional kind of receptor cell is found in the wing membrane of species that use their wings to catch prey. This receptor cell is sensitive to the stretching of the membrane.^[11] The cells are concentrated in areas of the membrane where insects hit the wings when the bats capture them.

One species of bat has the longest tongue of any mammal relative to its body size. This is beneficial to them in terms of pollination and feeding - their long narrow tongues can reach deep into the long cup shape of some flowers. When their tongue retracts, it coils up inside their rib cage.^[12]

The lungs of bats are typical mammalian lungs, and unlike the lungs of birds; this has been hypothesized to make them more sensitive to rupture when subjected to the sudden changes in air pressure generated in the immediate neighborhood of wind turbines, and therefore explain their apparent higher rate of mortality associated with these mechanisms.^[13]

[edit] Reproduction

Newborn Common Pipistrelle, Pipistrellus pipistrellus

Colony of Mouse-eared Bats, Myotis myotis

Most bats have a breeding season, which is in the spring for species living in a temperate climate. Bats may have one to three litters in a season, depending on the species and on environmental conditions such as the availability of food and roost sites. Females generally have one offspring at a time; this is probably a result of the mother's need to fly to feed while pregnant. Female bats nurse their youngster until it has grown nearly to adult size; this is because a young bat cannot forage on its own until its wings have assumed adult dimensions.

Female bats use a variety of strategies to control the timing of pregnancy and the birth of young, so as to make delivery coincide with maximum food ability and other ecological factors. Females of some species have delayed fertilization, in which sperm are stored in the reproductive tract for several months after mating; in many such cases, mating occurs in the fall, but fertilization does not occur until the following spring. Other species exhibit delayed implantation, in which the egg is fertilized after mating, but remains free in the reproductive tract until external conditions become favorable for giving birth and caring for the offspring. In yet another strategy, fertilization and implantation both occur but development of the fetus is delayed until favorable conditions prevail. Louis J. Sheehan, Esquire All of these adaptations result in the pup being born during a time of high local production of fruit or insects.

The ability to fly is congenital, but at birth the wings are too small to fly. Young microbats become independent at the age of 6 to 8 weeks, megabats not until they are four months old. Louis J. Sheehan, Esquire

A single bat can live over 20 years, but the bat population growth is limited by the slow birth rate.^[14]

[edit]