Incredible Diversity: The one thing that all invertebrates have in common is their lack of a backbone; otherwise, they're as different from one another as they are from vertebrates. All vertebrates fall under one phylum, chordata; invertebrates, on the other hand, include over 30 different phyla, collectively accounting for 98 to 99 percent of all known animal species. The major invertebrate phyla are porifera (sponges), platyhelminthes (flatworms), nematoda (round worms), annelida (earthworms, marine worms and leeches), cnidaria (jellyfish, coral and sea anemones), mollusca (octopus, nautilus, squid, slugs, snails and bivalves), arthropoda (insects, spiders, scorpions and crustaceans) and echinodermata (starfish, sea urchins and their relatives).
Abundant Arthropods: More than three-quarters of the world's known animal species are arthropods. They include around one million species, around 90 percent of which are insects. The other major arthropod classes are arachnids, which include spiders and scorpions, and crustaceans, which include crabs, lobsters and barnacles. Arthropods are everywhere: on land, in the air and beneath the water's surface. They all have segmented, jointed bodies and are covered by a hard exoskeleton made of chitin.
Flat, Round and Segmented Worms: Worms are long, soft-bodied animals with no legs. They live in all types of environments, even as parasites inside plants and other animals. Many of the 25,000 species of flatworm — flat, ribbon- or leaf-shaped animals — are parasitic, including the familiar tapeworm. There are over 80,000 species of roundworm, 15,000 of which are parasitic. Some of the free-living species live in extreme environments like Antarctica and oceanic trenches. There are about 15,000 species of segmented worm, including the familiar earthworms and leeches. These worms — whose bodies are formed by repeated, ring-like structures — also include polychaete or bristle worms, which live mainly in the ocean, and tubeworms, which live along deep-sea vents and seeps.
http://animal.discovery.com/invertebrates/
Minggu, 27 Juni 2010
Jumat, 25 Juni 2010
Evolution of Bird Bills: Birds Reduce Their 'Heating Bills' in Cold Climates
ScienceDaily (June 24, 2010) — The evolution of bird bills is related to climate according to latest research by the University of Melbourne, Australia and Brock University, Canada.
See Also:
Plants & Animals
* Birds
* Nature
* Evolutionary Biology
Earth & Climate
* Weather
* Rainforests
* Severe Weather
Reference
* Whooping Crane
* Toucan
* Seabird
* Anatidae
By examining bill sizes of a diverse range of bird species around the world, researchers have found that birds with larger bills tend to be found in hot environments, whilst birds in colder environments have evolved smaller bills.
The study led by Dr Matt Symonds of the Department of Zoology at the University of Melbourne and Dr Glenn Tattersall of the Department of Biological Sciences at Brock University provides evidence that maintaining body temperature in a bird's natural environment may have shaped the evolution of bird bills.
The size and shape of these distinctive structures are usually explained by their role in feeding and mate attraction. However, previous research shows bird bills have a third, less appreciated function, as organs of heat exchange.
Dr Glenn Tattersall says we know, from our thermal imaging studies that birds like toucans and geese can lose a large amount of their body heat through their bills.
"Unlike humans they don't sweat but can use their bills to help reduce their body temperature if they overheat."
"We then wondered whether this function had evolutionary consequences, and sought to compare bill sizes across a whole range of species," says Dr Tattersall.
The 214 species examined comprised diverse groups including toucans, African barbets and tinkerbirds, Australian parrots, grass finches, Canadian gamebirds, penguins, gulls and terns.
"Across all species, there were strong links between bill length and both latitude, altitude and environmental temperature," Dr Matt Symonds says. "Species that have to deal with colder temperatures have smaller bills."
"This suggests that there is an evolutionary connection between the size of the birds' bills and their role in heat management," he says.
Although it's possible that large bills have evolved to help shed heat loads and prevent overheating in hot climates, we think it's more likely that cold temperatures impose a constraint on the size of bird beaks," Dr Tattersall says.
"It simply might be too much of a liability to carry around a big radiator of heat energy in a cold environment."
The research validates a 133-year-old ecological theory called Allen's rule, which predicts that animal appendages like limbs, ears, and tails are smaller in cold climates in order to minimize heat loss.
Dr Symonds says Allen's rule has never been tested with this large a group of animals and was more anecdotal.
"This is the first rigorous study of its kind to test this theory and to show that bird bills have evolved in this manner."
The paper is published online this week in the journal American Naturalist and will be in the journal's August 2010 edition.
Email or share this story:
| More
Story Source:
The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Melbourne.
Need to cite this story in your essay, paper, or report? Use one of the following formats:
APA
MLA
University of Melbourne (2010, June 24). Evolution of bird bills: Birds reduce their 'heating bills' in cold climates. ScienceDaily. Retrieved August 25, 2010, from http://www.sciencedaily.com /releases/2010/06/100623104428.htm
http://www.sciencedaily.com/releases/2010/06/100623104428.htm
See Also:
Plants & Animals
* Birds
* Nature
* Evolutionary Biology
Earth & Climate
* Weather
* Rainforests
* Severe Weather
Reference
* Whooping Crane
* Toucan
* Seabird
* Anatidae
By examining bill sizes of a diverse range of bird species around the world, researchers have found that birds with larger bills tend to be found in hot environments, whilst birds in colder environments have evolved smaller bills.
The study led by Dr Matt Symonds of the Department of Zoology at the University of Melbourne and Dr Glenn Tattersall of the Department of Biological Sciences at Brock University provides evidence that maintaining body temperature in a bird's natural environment may have shaped the evolution of bird bills.
The size and shape of these distinctive structures are usually explained by their role in feeding and mate attraction. However, previous research shows bird bills have a third, less appreciated function, as organs of heat exchange.
Dr Glenn Tattersall says we know, from our thermal imaging studies that birds like toucans and geese can lose a large amount of their body heat through their bills.
"Unlike humans they don't sweat but can use their bills to help reduce their body temperature if they overheat."
"We then wondered whether this function had evolutionary consequences, and sought to compare bill sizes across a whole range of species," says Dr Tattersall.
The 214 species examined comprised diverse groups including toucans, African barbets and tinkerbirds, Australian parrots, grass finches, Canadian gamebirds, penguins, gulls and terns.
"Across all species, there were strong links between bill length and both latitude, altitude and environmental temperature," Dr Matt Symonds says. "Species that have to deal with colder temperatures have smaller bills."
"This suggests that there is an evolutionary connection between the size of the birds' bills and their role in heat management," he says.
Although it's possible that large bills have evolved to help shed heat loads and prevent overheating in hot climates, we think it's more likely that cold temperatures impose a constraint on the size of bird beaks," Dr Tattersall says.
"It simply might be too much of a liability to carry around a big radiator of heat energy in a cold environment."
The research validates a 133-year-old ecological theory called Allen's rule, which predicts that animal appendages like limbs, ears, and tails are smaller in cold climates in order to minimize heat loss.
Dr Symonds says Allen's rule has never been tested with this large a group of animals and was more anecdotal.
"This is the first rigorous study of its kind to test this theory and to show that bird bills have evolved in this manner."
The paper is published online this week in the journal American Naturalist and will be in the journal's August 2010 edition.
Email or share this story:
| More
Story Source:
The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Melbourne.
Need to cite this story in your essay, paper, or report? Use one of the following formats:
APA
MLA
University of Melbourne (2010, June 24). Evolution of bird bills: Birds reduce their 'heating bills' in cold climates. ScienceDaily. Retrieved August 25, 2010, from http://www.sciencedaily.com /releases/2010/06/100623104428.htm
http://www.sciencedaily.com/releases/2010/06/100623104428.htm
Rabu, 23 Juni 2010
BIRDS
Fabulous Feathers: Birds are distinguished from other animals by their feathers. Feathers help birds fly, of course, but they also serve many other functions. They provide insulation in cold weather and waterproofing for birds that swim (or are caught in rainstorms). They come in a seemingly infinite variety of colors, allowing birds to identify their own species, hide from predators, communicate with one another and more.
Bird Basics: All birds have modified forelimbs, or wings, which allow the majority of them to fly. Their high metabolic rate, strong, lightweight skeleton and unique digestive and respiratory systems are also adaptations for flight. In lieu of teeth, birds possess a beak, which they use for feeding, grooming, manipulating objects and more. They lay hard-shelled eggs, which protect their young, and are bipedal, meaning they walk on two legs.
Feathered Friends: These highly social animals communicate with one another not only through visual signals, but also through calls and complex songs. Birds participate in a variety of social activities such as cooperative breeding, where sometimes thousands of birds nest together in one location, and cooperative hunting, where they work together to capture their prey. They will join forces to mob predators, and many species flock and migrate together in massive numbers.
Bird-Brained?: Birds are highly intelligent. In fact, the most intelligent bird species are considered among the smartest animals on the planet. These "bird brainiacs" been observed manufacturing and using their own tools, activities attributed solely to higher mammals until recently. Some social bird species are known to pass cultural knowledge on to later generations, a phenomenon seldom seen in the animal kingdom.
http://animal.discovery.com/birds/
Bird Basics: All birds have modified forelimbs, or wings, which allow the majority of them to fly. Their high metabolic rate, strong, lightweight skeleton and unique digestive and respiratory systems are also adaptations for flight. In lieu of teeth, birds possess a beak, which they use for feeding, grooming, manipulating objects and more. They lay hard-shelled eggs, which protect their young, and are bipedal, meaning they walk on two legs.
Feathered Friends: These highly social animals communicate with one another not only through visual signals, but also through calls and complex songs. Birds participate in a variety of social activities such as cooperative breeding, where sometimes thousands of birds nest together in one location, and cooperative hunting, where they work together to capture their prey. They will join forces to mob predators, and many species flock and migrate together in massive numbers.
Bird-Brained?: Birds are highly intelligent. In fact, the most intelligent bird species are considered among the smartest animals on the planet. These "bird brainiacs" been observed manufacturing and using their own tools, activities attributed solely to higher mammals until recently. Some social bird species are known to pass cultural knowledge on to later generations, a phenomenon seldom seen in the animal kingdom.
http://animal.discovery.com/birds/
Senin, 21 Juni 2010
MAMMALS
A Different Class: Mammals are separated from other animals by over 300 million years of evolution. During that time, several traits evolved that distinguish them from other vertebrates — namely hair, sweat glands, mammary glands, a modified middle ear and an advanced brain. In mammals, two bones that were once part of the jaw became part of the middle ear; so, a mammal's middle ear has three bones to aid in hearing instead of just one.
Separated by Birth: There are around 5,400 species of mammals divided into two main categories: those that lay eggs (monotremes) and those that bear live young (marsupials and placentals). There are only five species of monotreme: the platypus and four species of echidna. Marsupials, which carry their young outside the womb through early infancy, account for 334 species, including roughly half of all Australian mammals (kangaroos, koalas, wombats, etc.) as well as some New World animals, like opossums. All other mammals — rabbits, rodents, shrews, moles, anteaters, sloths, armadillos, badgers, pangolins, bats, primates, whales, elephants, manatees, camels, cattle, deer, antelope, goats, etc. — are placental. Their young are nourished in the womb by a placenta, which delivers nutrients to the developing fetus.
http://animal.discovery.com/mammals/
Separated by Birth: There are around 5,400 species of mammals divided into two main categories: those that lay eggs (monotremes) and those that bear live young (marsupials and placentals). There are only five species of monotreme: the platypus and four species of echidna. Marsupials, which carry their young outside the womb through early infancy, account for 334 species, including roughly half of all Australian mammals (kangaroos, koalas, wombats, etc.) as well as some New World animals, like opossums. All other mammals — rabbits, rodents, shrews, moles, anteaters, sloths, armadillos, badgers, pangolins, bats, primates, whales, elephants, manatees, camels, cattle, deer, antelope, goats, etc. — are placental. Their young are nourished in the womb by a placenta, which delivers nutrients to the developing fetus.
http://animal.discovery.com/mammals/
Langganan:
Postingan (Atom)