Vertebrates
by Kendra Brewer, Hunter Smith,
Matt Tripp, and Jessica Richardson
What are Vertebrates?????
Vertebrates are the only animals with a "backbone." Of the more than two million species of animals, fewer than 50,000 are vertebrates. Vertebrates are chordates with a backbone either of cartilage or bone and a brain located inside a protective chamber of the skull bones.
Characteristics of Vertebrates
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the backbones are made of either cartilage or bone |
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all vertebrates have craniums |
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vertebrates have closed circulatory systems |
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closed circulatory system - heart pumps blood through vessels (arteries, capillaries) |
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vertebrates skin have two regions: an outer epidermis and an underlying dermis |
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the dermis region is mainly dense connective tissue with mainly elastic fibers (which resist stretching) and collagen fibers (which impart strength) blood vessels, lymph vessels, and receptor endings of sensory nerves thread through it |
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epidermis is like a puffy pastry |
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it is a stratified epithelium |
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Keratinocytes - most abundant cell in epidermis |
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Vertebrates eyeballs have three germ layers: endoderm, ectoderm, and mesoderm |
Endangered Species
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Cheetah |
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Florida Panther |
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Pheasant |
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Wolves |
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Bat |
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Harp Seal |
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Panda |
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African Elephant |
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Gorilla |
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Lion |
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Leopard |
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Sea Turtle |
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Whales |
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Desert Tortoise |
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Crocodile |
Evolution
In the Cambrian times free-swimming species originated and gave rise to two kinds of fish - those without and those with jaws. From one of these types came all vertebrate lineages that followed. The vertebrate lineages starts with the ancestral vertebrates which are jawless fish. The lineage continues as follows: cartilaginous fish, bony fish, amphibians, reptiles to birds, and from reptiles came mammals.
Cartilaginous Fish ------- Chondrichthyes
850 species includes: skates, sharks, and chimaeras
Bony Fish ------- Osteichthyes
Most numerous and diverse vertebrates making up all but 4% of modern fish species.
includes: ray-finned, lobe-finned, and lungfish
Amphibians ------- Coelacanth
fish moved onto land because of rise and fall of sea levels
All salamanders, frogs, toads, and caecilians today are descendants of the first amphibians
Reptiles ------- Amphibians gave rise to reptiles (reptilia)
Reptiles were the first to escape from the aquatic habitats.
Crocodilians were first animals with a
muscular, four-chambered heart fully separated into two halves.
included: dinosaurs from the Triassic Era to Cretaceous Era. Today
includes: crocodilians, turtles, tuataras, snakes, and lizards.
Birds ------- Aves
descendents of tiny reptiles
Archaeopteryx leads to modern birds.
There are almost 9,000 named species of birds.
Mammals ------- Mammalia
Mammals are the only vertebrates with hair and mammary glands.
From mammals came primates, hominids, then humans.
So here we are today - HUMANS!!!!
We are breathing, talking, walking, hairy, child-bearing descendents of a jawless fish. Take more time to trace the path of vertebrates from fish to humans!!!
Web
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Embryonic Development
Most vertebrates begin life as fertilized eggs and then proceed through different developmental stages to becoming an adult. During early developmental stages, most embryos of vertebrates resemble each other.
Gene mutation that may have caused drastic changes in the development of embryos also had changes on the adult stages of life. Embryonic induction is when exposure to a gene product released from one tissue can change the developmental fate of an adjacent embryonic tissue.
The evolution of animal body plans differ by physical, architectural, and phyletic constraints. During the embryonic period, all vertebrates develop a primitive streak, neural tube, somites, and pharyngeal arches. This primitive streak establishes the body's anterior-posterior axis and bilateral symmetry.
Web Links
http://www.ucmp.berkeley.edu/vertebrates/vertintro.html
http://phylogeny.arizona.edu/tree/eukaryotes/animals/chordata/terrestrial_vertebrates.html
http://www.cyhaus.com/marine/verts.htm
http://www.kheper.auz.com/gaia/biosphere/vertebrates/vertebrates.htm
http://www.ultranet.com/~jkimball/BiologyPages/V/Vertebrates.html
http://depts.washington.edu/vertp/
http://www.neartica.com/paleo/verts/vertphy.htm
Works Cited
Starr, Cecie. Biology, Concepts and Applications, Fourth Edition. USA. Brooks/ Cole, 2000.
11/02/01
