Biology 102Lecture 25Outline of Last Lecture:I. Clicker Questions II. ChordatesOutline of Current Lecture:I. Clicker QuestionsII. ChondricthayansIII. Ray Finned IV. Lobe FinnedClicker QuestionsAll chordates are vertebrates.a. True b. FalseThe sea squirt (tunicate) is a chordate. But looking at the adult, we don’t see the four chordate characteristics. Why then do we characterize the sea squirt as a chordate?a. The four characteristics are seen in the larvab. The four characteristics are seen in the adult if you look close enoughc. The four characteristics aren’t seen at all in sea squirtsd. Sea squirts are chordatesTetrapods, with their muscular fins supported by stout bones, gave raise to the amphibians. Hypothesize how this might have happened? What could they have been using their stout fins for?a. Moving to new environments for resourcesb. Escaping predators c. Stability in currentsd. Movement along the edgee. Prop themselves up(all of these answers are correct)ChondricthayansBest examples of chondricthayans are sharks and sting raysProperties:Biology 102- A cartilage skeleton- Most chondricthayans are predators. The soft skeleton allows them to swim fast- Keen sense of smell- Sharp vision- Electrosensors on head that detect minute electrical fields- Their bodies are adapted for life on the bottom of the ocean (flat)Ray FinnedRay finned fish also known as bony fishProperties:- Flattened scales covered with mucous reduces drag while swimming, makes it easier to swim- Operculum (flaps on the side of the head covering the gills)- Swim bladder (gas filled sac): it inflates and deflates with gas in order to move up or down in the water; buoyancyLobe FinnedProperties:- Muscular fins, very thick stout bones- Homolougous to bones in amphibians3 Lineages:- Lung fisheso Can go to the surface of the water and breathe air- Tetrapodso Live in still water- CoelacanthsAmphibians were the first vertebrates to make it to
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