The most prominent organ is the liver, dark brown in color, and taking up most of the abdominal cavity. Then pin the muscle to the dissection tray. Use forceps and a scalpel to separate the muscle from the tissue below. Then make horizontal incisions above the rear legs and between the front legs. When you reach the area just below the front legs of the frog, turn your scissors sideways to cut through the chest bones and avoid damaging the heart and lungs. Be careful not to cut too deeply and damage the internal organs. Create one long incision along the midline of the frog from between the hind legs to the neck. Repeat the same procedure to cut through the muscles.Pin the skin flaps to the dissection tray.Pick up a skin flap with forceps and use a scalpel to separate the skin from the muscle below.Cut the skin horizontally above the hind legs and below the front legs creating skin flaps.Use scissors to cut the skin along the midline of the frog starting between the hind legs and ending at the neck. Lift up the skin with forceps midway between the hind legs of the frog.Place the frog belly side up in the dissecting tray.They are located in the angle of the jaw. Eustacian tubes (2) openings that lead to the ears.Glottis, slit where air passes through to enter the trachea, which leads to the lungs.Esophagus, the opening leading to the stomach.Maxillary teeth (smaller) located on the sides of the upper jaw.Two vomerine teeth located in the middle of the roof of the mouth.You can cut the hinges of the jaw if necessary. Turn the frog over and open the mouth as wide as you can.How many phalanges are on the hindfeet? The forefeet? Which pair of limbs is the longest? How does this assist the frog in its movement? Identify the eyes, covered by a nicitating membrane, the external nares (nostrils), and the tympanum located behind each eye.Place the frog in the dissection pan legs down.Dissect a frog following the procedure below. Our vertebrate chordate example of today’s lab is the frog. Make sure you can identify all four chordate characteristics on the model. List the four chordate characteristics below. It contains all four chordate characteristics. The lancelet is an example of a cephalochordate. We don’t have any urochordate examples in the lab. There are two groups of invertebrate chordates, the cephalochordates and the urochordates.Please make observations on the available specimens and fill in the chart below.Īccess the page “Reading: Chordates.” Questions The preserved echinoderm specimens will be on display, but may differ from the ones directly mentioned in the lab handout.Make sure you can identify both structures. The digestive glands are brown and typically on top of the off white gonads. In the starfish arms you should find both digestive glands and gonads.Can you differentiate between the two stomachs on your specimen? The starfish has a two part stomach, the upper pyloric stomach and the lower cardiac stomach.The starfish has plates located underneath the skin for protection and support.This is the water entrance point for the water vascular system used for movement. Find the sieve plate/madreporite on the aboral side.The skin gills are smaller and used for gas exchange. The spines are longer are used for protection. Try to differentiate between the spines and the skin gills. How many rows of tube feet does your starfish have? Tube feet are used for locomotion powered by the water vascular system.
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