Microbat
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de:Fledermäuse da:Flagermus es:Murciélago nl:Vleermuis fr:Chiroptère ja:コウモリ pl:Microchiroptera zh:蝙蝠
The microbats constitute the suborder Microchiroptera within the order Chiroptera (bats). Other English names are "insectivorous bats", "echolocating bats", "small bats" or "true bats". All these names are somewhat inaccurate, because not all microbats feed on insects, and some of them are larger than small megabats.
The distinctions between microbats and megabats are:
- Microbats use echolocation, whereas megabats do not.
- Microbats lack the claw at the second toe of the forelimb.
- The ears of microbats don't form a closed ring, but the edges are separated from each other at the base of the ear.
- Microbats lack the underfur; they have only guard hairs or are naked.
Most microbats feed on insects. Some of the larger species hunt birds, lizards, frogs or even fish. Microbats that feed on the blood of large mammals (vampire bats) exist in South America. Microbats are 4 to 16 cm long.
Echolocation
Bats are the most famous examples for echolocation among animals. Only the microbats (and not the megabats) are able to orient this way.
The ultrasounds emerge in the larynx and are expelled through the nose or the open mouth. They have a frequency of 20,000 to 100,000 hertz and are inaudible for the human ear. Due to the high frequency the sounds are concentrated to a narrow beam. Some species have a funnel-shaped nose in order to improve the beam. The range of this beam is up to 5 m.
There are 800 species of microbats, each of them with a different behaviour pattern. Therefore there are great differences between the echolocation systems of the single species. The following is not valid for all microbats, but for most of them.
Every 150 milliseconds an ultrasound is expelled. That resembles roughly the period of a wing flap or a breath. The sound is reflected by surrounding objects and reaches the bat's ear. The bat is able to determine the distance of objects from the time between expelling and hearing the sound. The sounds may come in shorter intervals, when the bat is going to land or approaching to an obstacle.
Echolocation is not used only for avoiding collisions with objects, but also for hunting the prey. The prey is seized with the mouth, in the case of large prey sometimes with the wings.
Experiments with bats showed that a bat is able to "hear" a wire as thin as 0.08 mm. The echolocation also enables the bat to analyse the surface of an object, so it won't confuse a prey with a plastic object.
Some moths have developed a protection against bats. They are able to hear the bat's ultrasounds and flee as soon as they notice these sounds, or stop beating their wings for a period of time to deprive the bat of the characteristic echo signature of moving wings which it may home in on.
Classification
This is the classification according to Simmons and Geisler (1998):
- Superfamily Emballonuroidea
- Family Emballonuridae (Sac-winged bats or sheath-tailed bats)
- Superfamily Rhinopomatoidea
- Family Rhinopomatidae (Mouse-tailed bats)
- Family Craseonycteridae (Bumblebee Bat or Kitti's Hog-nosed Bat)
- Superfamily Rhinolophoidea
- Family Rhinolophidae (Horseshoe bats)
- Family Nycteridae (Hollow-faced bats or Slit-faced bats)
- Family Megadermatidae (False vampires)
- Superfamily Vespertilionoidea
- Family Vespertilionidae (Vesper bats or Evening bats)
- Superfamily Molossoidea
- Family Molossidae (Free-tailed bats)
- Family Antrozoidae (Pallid bats)
- Superfamily Nataloidea
- Family Natalidae (Funnel-eared bats)
- Family Myzopodidae (Sucker-footed bats)
- Family Thyropteridae (Disk-winged bats)
- Family Furipteridae (Smoky bats)
- Superfamily Noctilionoidea
- Family Noctilionidae (Bulldog bats or Fisherman bats)
- Family Mystacinidae (New Zealand Short-tailed bats)
- Family Mormoopidae (Ghost-faced bats or Moustached bats)
- Family Phyllostomidae (Leaf-nosed bats)
External links
- Bat World Sanctuary (http://www.batworld.org)