Myxinia+and+Cephalsapidodorphi

**Kingdom:** Animalia

 * Phylum:** Chordata
 * Class:** Cephalaspidomorphi/Myxini
 * Germ Layers:** Endoderm, Mesoderm, Ectoderm
 * Symmetry:** Bilateral Symmetry
 * Coelom:** Has a coelom




 * Body Plan:** The lamprey is shaped similarly to the eel. The lamprey has a buccal funnel for a mouth, and has teeth around the opening of the mouth as shown in the picture above. A lamprey has gill slits on the sides of its head, which are behind the eye of each side. The lamprey has a nostril (imagine a blow hole of a whale, it looks like that) located on the top of its head in between the eyes. Continuing on down the body of the lamprey, the lamprey has an anterior dorsal fin, posterior dorsal fin, and a caudal fin. The lamprey has vertebrae. The hagfish has a partial skull, but no vertebrae and no bones, only cartilage. The hagfish has poorly developed eyes, so eyesight is bad. The hagfish has four tentacles near the mouth for sensing, and it has five to fifteen pairs of gills. Neither has a stomach.

Diagram available here: []


 * Habitat:** Lamprey larvae grow in freshwater, feeding on microorganisms and detritus. They live in freshwater streams from four to six years, and then move out to sea, although landlocked lamprey will move out to the Great Lakes. The lamprey live out in the open water for anywhere from a year to two years, then move back to their original habitats to spawn. Hagfish live at the bottom of the ocean in the mud so that the hagfish can burrow into the ground when needed.


 * Movement:** The lamprey moves from side to side, snaking its body through the water. The hagfish uses its tail to move through the water.


 * Skeletal System:** The lamprey has no bones, but has cartilage for support. The lamprey has a few cartilage blocks around its notochord which resembles a backbone. The lamprey also has a cartilage framework to support the gill region and a cartilage braincase.


 * Evolutionary Advancement:** Lampreys come from the earliest vertebrates. They are thought to have split from other vertebrates (which led to modern fish) from around 500 million years ago.


 * Special Adaptations:** The mouth of the lamprey is circular with 11 to 12 rows of teeth that encircle the mouth. This is a distinguising feature of the lamprey that allows it to attach itself to other fish to feed. The hagfish produces a slime that protects it from predators, and some believe that the slime of the hagfish is strong enough to suffocate its prey by clogging the gills of any fish that comes in contact with it. The slime also has tiny fibers in it that strengthen the slime and make the slime hard to remove. The hagfish can tie itself into a knot to escape the slime.
 * Feeding Patterns:** The adult lamprey attaches itself onto the side of its prey and feeds on the flesh and fluids of the prey, while larval lamprey filter feed on planktonic drift. Adult lampreys have secrete an anticoagulant that keeps the wound on the prey from healing; lampreys often feed until the death of the prey. Hagfish feed by burrowing themselves into prey and eating the animal from the inside out. When there are no big animals for the hagfish to feed on, they also eat worms and small inverebrates.


 * Respiration:** Both the hagfish and the lamprey have gill passages that enlarge and form pouches - these pouches have gill filaments that serve as a surface for gas exchange. Water goes in through the mouth and is passed through the pharynx, then moves on to the respiratory tube. The respiratory tube contains gill pouches and contain gill lamellae which increase the surface area of the respiratory structures. The gill lamellae contain capillary beds that extract dissolved oxygen from the water. While the lamprey is feeding, water passes through the external gill slits and oxygen is taken in that way.


 * Circulation:** Lamprey have a series of vessels and arteries that supply nutrients and oxygen, and carry away wastes such as carbon dioxide through its blood. The lamprey has a two chambered heart. The hagfish has a three chambered heart, and "accesory" hearts.
 * Excretory:** The main organ of the excretory system is the kidney which filters out waste from its blood. In salt water, lampreys excrete a highly concentrated urine while in freshwater they excrete an extremely dilute urine. Hagfish also use their kidneys as their main excretory organ. Both have an anus.


 * Nervous:** Both have a central nervous system, but no sympathetic nervous system.


 * Reproduction:** After feeding for about two years in the open water, the lamprey returns to freshwater and its digestive system breaks down. Enamel caps on its teeth fall off so that the lamprey cannot feed, then the lampreys go blind. They travel upstream to spawn, and use their mouths to hold onto surfaces like rocks to overcome obstacles. Spawning season starts in late May and goes to early summer. Sea lampreys create gravel nests, and the female lay an average of 200,000 eggs in nests the males create. . The eggs take 10-13 days to hatch and then the larvae travel downstream to burrow in the mud of the still water. The larvae live there for 4-8 years in the mud, feeding on planktonic drift. The hagfish fertilizes externally - females lay around 30 large eggs that have velcro like attachments on the ends to stick together. Hagfish are thought to be hermaphroditic.

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