The last physical job you had in component II was to cut off the tips of the trivium rays. Girlfriend were also instructed to research the pictures and also diagrams listed to determine the frameworks in the cross-section watch of the ray.
Locate the coelom and be ready to identify its location. Raise your hand because that the teacher to confirm that you have successfully figured out this space. (2 pts)
1. Utilizing the hand lens research the reduced end the the beam to find the tube feet and also ampullae. In ~ the external finish of eachtube foot is a sucker. The internal finish of a tube foot creates the ampullae, a small, muscular, bulblike sac.

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2. Observe the the ampullae and also tube feet are uncovered along the leaf of a zipper-like ridge the extends the whole length the the ray. The ridge is composed of rows that ossicles, or bones plates, i beg your pardon are installed in the soft human body wall. This plates make up the endoskeleton, or inner skeleton, of a starfish. This meshwork that plates also gives rigidity come the human body of the starfish and also protection to the pipe feet while enabling the rays to bend and twist.
3. Research the cross ar which shows how the lateral canals affix the pipe feet come the radial canal. This radial canal operation the complete length of every ray. Radial canals space very tiny and they room not clearly shows in the kept specimen unless the specimen has actually been especially injected v dye. Water moves from the madreporite to the ring canal (neither displayed here) come the radial canal come the lateral canals i beg your pardon then to fill the ampullae. The water save on computer in the ampullae is provided to move the tube feet up and also down.


When dissecting the starfish, you will be uncovering layer by class the various systems in the starfish.1. An initial you will certainly cut increase the sides the the rays and also then across to pull up the skin. This is a daunting task. Be careful to try and not damage the inner structures that the starfish when you are cutting increase the sides. as soon as pulling increase the skin, use a probe or tweezers to different the skin indigenous the interior structures. It is ideal to usage a pair of pointed scissors. Why aren"t we utilizing a scalpel or razor? making use of a scalpel or razor causes too much damage to the inner structures as soon as pressure is moved down top top the skin in the process of cutting it.2. After ~ you have actually the skin turn off of the tops of the rays, the next step is to cut the skin off of the main disc keeping the madreporite in tact and carefully lifting the skin for this reason the interior organs room not damaged. The easiest way is to execute this is to progressively cut little pie-shaped wedges off until you get every one of the skin eliminated from the central disk.3. Bespeak of inner observations and also identifications: 1st layer is the digestive System; second layer is the sex-related Reproductive System, and the 3rd layer is the Skeletal and also Water-Vascular SystemWatch the following video clip as a PREVIEW of what you will certainly be doing. That is valuable so girlfriend will have an idea the what you are trying to find with each layer of dissection. execute not monitor the directions in the video clip as you are watching it. You will follow the created directions that follow this content Box.

watch that many of the an are in the beam is occupied by the pyloric caeca, two long digestive glands. Every ray includes caeca, or pouches. (They are usually some shade that brown and also look feathery.) The ducts, or tubes, bring enzymes type the caeca to the stomach.

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Locate the quick tubular intestine the extends from the stomach come the anus in the center of the central disc. Sometimes this it s okay damaged if removing the flap extending the central disk.
Attached come one next of the intestine is a two-or-three branched minister caeca. Part or all of these, the intestine, anus, and also intestinal caeca, may not it is in distinguishable in her specimen.
Starfish have two stomachs; the cardiac stomach, and also the pyloric stomach. The cardiac is a sack-like stomach found in the center of the body. It can be propelled out that the starfish's body and used come engulf food. Some starfish pressure open mollusks (clams) through injecting their stomachs right into the shells. Through the stomach inside, the starfish digests the mollusk in the shell. The pyloric stomach is associated by 2 pyloric caeca- hole tubes that absorbs nutrient from that food. The pyloric stomach is closest come the aboral next of the starfish and is on top of the cardiac stomach i beg your pardon is straight over the mouth on the ventral next of the starfish. Starfish eat countless things, prefer barnacles, snails, sea urchins, clams, and also mussels.