Incredible Diversity of bats Draft #2

This discussion topic submitted by Devin schenk on 7/7/98.

The Incredible Diversity of bats

Bat Facts
- approximately 1000 identified species of bats worldwide
- accounts for approximately 25% of all mammal species
- Diet: 70% eat insects; 20% eat fruit or nectar; the rest eat blood, aquatic animals, or a mixture

evolution

- oldest fossils are 50 million years old and allowing for evolution they are probably 65-100 million years old
Ö great radiation of diversity of bats happened at the same time as angiosperms became prolific most likely a co-relation
Ö birds were already very abundant by the time bats appeared

Flight
Ö bats probably started off as a tree dwelling animal that developed skin between its fingers that allowed it to glide, and from there the development of flight could have eventually evolved
ÖIt is theorized that the development of echolocation happened at the same time as flight developed in bats
Ö bats have many of the same adaptations for flight as birds: high respiratory rates, highly aerobic muscles, large heart
- large sternum in birds is missing but a large ligmentous sheet serves the same purpose
- bones are very small and rigid for strength and lightweight
Ö bat wing is very similar to a human arm - four fingers and a thumb, forearm, upper arm
Ö bats muscular structure is much more complex than a birds - 5 downstroke and 2 upstroke muscles for bats, as compared to 1 downstroke in birds ( bats do terrestrial locomotion as well as aerial)
Ö mating - one young a year (less weight), storage of sperm and delayed implantation

taxonomy
Ö megabats - Old world - fruit bats - closer to primate lineage
Ö microbats - Old and New world insectivores - closer to rodent lineage - echolocation very advanced

Ecological Importance
seed Dispersal
Ö Fruit bats eat up to 3 times their body weight a night
Ö seeds pass through very quickly
Ö a short-tailed fruit bat can scatter 60,000 seeds in a single night
Pollinators
Ö Nectar eating bats visit many tropical tree flowers and work as pollinators
Insect Consumers
Ö bats can eat up to one bug every 6 seconds which is 600 bugs/hour
Ö many of these bugs are mosquitoes, crop pests (moths, locusts, grasshoppers)
Vampire bats
Ö located only in New World Tropics
Ö only 3 species out of the 1000 are vampires

Costa Rican bats
There are 103 identified species of bats in Costa Rica
Ö makes up 50% of the mammal species in the country
Ö half of these bats are have fruit or nectar in their diets

Vampire bats
Ö 3 species: Common, Hairy Legged, White winged
Ö Hairy legged and White winged are both rare and feed on birds
Ö Common Vampire
- only bat in the world that feeds on the blood of mammals
- evolved to feed on wild animals, but has almost entirely switched to feeding on livestock
- with the increase in the beef industry in Latin America the vampire bat population has grown and has reached pest status
- estimated $100 million dollars in damages do to the transmission of rabies and other diseases to livestock
- most Latin Americans do not distinguish between bat species and as a result kill tens of thousands of beneficial bats a year in eradication campaigns - Fruit and insect eating bat colonies are often victims in indiscriminate blasting of cavess
- anti-coagulant helps the bat keep the wound from closing, some thought of how this chemical could help human heart patients
fisherman (Bulldog) bats
Ö found in Tortuguero
Ö uses echolocation to locate fish
- can detect when the fins of minnows break the surface
- can detect an object as thin as a human hair on the surface of water
Ö has huge feet and long claws for fishing
Ö and large cheeks where it stuffs the minnows it catches - these cheeks are what gives it a bulldog look
Ö feeds on beetles and moths during the rainy season

False Vampire
Ö largest bat in the New World (3 ft wingspan)
Ö captures birds, other vertebrates, other bats and kills them with a bite to the neck

Fringed-lipped Bat
Ö can distinguish between poisonous and nonpoisonous frogs with echolocation



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