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Biology Test 3 2


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-phylum to which humans belong.

-bodies of chordates have hard components

-highly specialized with intricate bodies and comlex organization
Chordate Groups
-Chordates have two invertebrate groups, the lancelets and the sea squirts

-Chordates have one vertebrate group
-slender support rod that runs down the back of the animal

-sometimes present only in the embryo
Pharyngeal Slits
-at some stage of developlment, the pharynx of a chordate has slits.

-in some chordates, the pharyngeal slits develop in the embryo and are retained in the adult stage.

-sometimes appears only in embryo,

-other times, Pharyngeal slits develop in embryou stage and remain for adult stage.
Dorsol Hollow Nerve Cord
-the dorsal hollow nerve cord is on the back (dorsal) surface, is hollow, and surrounds a fluid filled cavity
-the body of a chordate also has a tail that extends beyond the anus in at least one stage of development.
Sea Squirts
-sea squirts are also known as tunicates and belong to an invertebrate group of chordates that are called the urochordates.
-Plankton are organisms that are carried around by water current because they cannot swim or because they cannot swim strongly.
-Lanceletts belong to an invertebrate group of chordates that are known as the cephalochordates
Lanceletts contain 4 chordate characteristics as adults:
-notochord, pharyngeal slits, dorsal hollow nerve cord, and a tail that extends beyond the anus.
Lanceltess feed by
-filter feeding.

-water enters the mouth through currents created by cilia, passes the pharynx where particles are filtered out, and exits through the pharyngeal slits.
-are called vertebrates because they have vertebral columns.

-A vertebral column is a structure made of a seperate bony or cartilagenous vertebrae that form a firm backbone for the animal.
The vertebrates are seperated from
-each other by pads of cartilage known as invertebral disks.

-the earliest vertebrates mainly relied upon a strong notochord.
-evolutionary advance for vertebrates that serves as a "braincase" made of carilage that encloses and protects the brain and provides support for sensory organs.
Jawless fishes
-jawless fishes were the earliest fossil vertebrates

-JFs relied upon muscles in their pharynx to pass water through their bodies.

-these muscles then created a "pump" to suck loose mud and sediments from the ocean floor into the mouths of jawless fishes
Food process continued

-then, the food particles were collected out of the mud and passed into the digestive tract
The only living Jawless fishes are the

-Lampreys and the Jawfish. They have a single nostril located in the middle of the head.

-mouth is round or oval

-are marine and look like eels. They are scavengers which feed on dead or dying invertebrates and fishes.

-their tongues have rough projections which they use to scrape tissue off their food.

-most primitive of living vertebrates

-are parasitic jawless fishes. A parasitic lamprey will grab onto live prey with its sucker like mouth and use its tongue to rasp away its flesh.

-occurs mainly in fresh water.
Cartilagenous Fishes

-are composed mainly of cartilage

-have cone shaped scales called placoid scales

-have jaws which enabled them to bite and crush prey.

-include sharks, rays, and skates
Cartilagenus Fish fins:
-C Fish have two pairs of fins: pectoral fins located in the front, and pelvic fins located in the back.

-paired fins provide stability, support, and the ability to maneuver
Bony Fish
-has more different vertebrate animals than any other group

-internal skeleton made of bone

-has swim bladder, a gas filled internal structure that allows the fish to maintain its position in the water without expending a great deal of energy.
Bony Fish Fins
-the majority of bony fish fins are supported by slender rods or rays. These are often called "ray-finned fishes"
"Fleshy-Finned" or
"Lobe-Finned" Fishes
-another type of bony fish where the fins are are at the end of appendages that project from the body of the fish.

-the appendages are supported by bones

-gave rise to first terrestrial invertebrates, the amphibians.
The only living Lobe-finned fishes today are
-the lungfishes and the coelacanth
-were the first group of vertebrates to move to land.

-usually divided into 3 groups, two of which are extinct and known only from fossils, and the third group consists of modern amphibians.
Modern Amphibins include
-newts, salamanders, caecilians, frogs and toads.
Amphibian Evolutionary Changes
-fins replaced by jointed limbs

-ankles and wrists also evolved.

-bones that supported the fins had to evolve into limb girdles that attach the limbs to the rest of the internal skeleton

-vertebral column had to become larger to support girdles for limbs.
Amphibian reproduction
-amphibians must lay their eggs in water or in a moist habitat.

-frogs and toads still have external fertilization, where the eggs and sperm are released outside the body of the parents of the parents
Amphibian breathing techniques
-have paired lungs that are usually small and have a few internal compartments.

-some salamanders don't have any lungs
Importance of Amphibian Skin
-due to the reduced lung surface, the majority of an amphibian's gas exchange occurs across its moist skin. If the skin dries out, the animal cannot exchange sufficient oxygen and carbon dioxide and it dies.

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