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1. Provide a brief description of the fishes citing characteristics that would distinguish them from all other animals: They have a vertebrae that surround their spinal cord and provide the primary axial support They have a skull that protects the brain All but hagfish and lamprey have paired fins They have gills They have a torpedo shaped body 2. What characteristics distinguish hagfishes and lampreys from all other fishes? Living jawless fishes include hagfishes and lampreys. Members of each group lack a jaw, internal ossification, scales, and paired fins. Both have naked skin, no paired appendages, and not distinct stomach. How do they differ in morphology from each other? Hagfish have 5 to 16 pairs of gills; lampreys have 7 pairs of gills. Hagfish have pronephric and mesonephric kidneys; lampreys have an opisthonephric kidney. 3. Describe the feeding behavior in hagfishes and lampreys. differ?

How do they

Although almost completely blind, a hagfish is quickly attracted to food, especially dead or dying fish, by its keenly developed senses of smell and touch. Using two toothed, keratinized plates on its tongue that fold together in a pincer-​-like action, the hagfish rasps bits of flesh from its prey. For extra leverage, The hagfish often ties a knot in its tail, and then passes the knot forward along its body until it is pressed securely against the side of its prey. There are 20 species of lampreys in North America, of which about half are parasitic; the rest are species that never feed after metamorphosis and die soon after spawning. These non-​-parasitic lampreys' digestive tract degenerates to a nonfunctional strand of tissue. The parasitic lampreys attach themselves by their sucker-​-like mouth to fish and use their sharp, keratinized teeth to rasp through flesh and suck body fluids. When gorged the lamprey releases its hold but leaving the fish with a large wound. The hagfish as described eats off of dead or dying fish. The hagfish also eats the flesh of the dead or dying fish. Lampreys on the other hand, attach to living fish and extract blood. Once full the lamprey releases and the fish may live, but with a wound. 4. Describe the life cycle of sea lampreys, Petromyzon marinus, and the history of their invasion of the Great Lakes. In North America, all lampreys (marine and freshwater) spawn in the winter or spring in the shallow gravel of freshwater streams. Males begin building nests and are joined later by females. Using their oral discs to lift stones and pebbles and using vigorous body vibrations to sweep away light debris, they form an oval depression. As the female sheds eggs into the nest, the male fertilizes them. The sticky eggs adhere to pebbles in the nest and soon become covered with sand. Adults die soon after spawning. Eggs hatch about 2 weeks later, releasing small larvae called ammocoetes, which then burrow into the mud or sand and become filter feeders.The larvae exits as filter feeders for 3-​-7 years and then rapidly metamorphose into adults.The now parasitic adult either migrates to the sea or remains landlocked. The sea lamprey first entered the Great Lakes between 1913 and 1918 when the Welland


Canal around Niagara Falls was deepened. The lamprey moved through the Great Lake system; destroying the lake trout industry. 5.

In what ways are sharks well equipped for a predatory life habit?

Sharks have three features that contribute significantly to their predatory life style; placoid scales, lateral-​-line system, and ampullae of Lorezini.

Placoid Scales: ​ these are modified anteriorly to form replaceable rows of teeth in both jaws.

Lateral-​-line System:​ this contains a receptors that allows the shark to locate prey from long distances by sensing low-​-frequency vibrations with mechanoreceptors. These receptor organs are called neuromasts. Ampullae of Lorenzini:​ these are electroreceptors on the shark's head that guide the shark to their prey by detecting the bioelectric fields that surround all animals. 6. What function does the lateral-​-line system serve? located?

Where are receptors

The lateral-​-line system is composed of special receptor organs called neuromasts in interconnected tubes and pores extending along the sides of the body and over the head. These mechanoreceptors helps the shark locate prey from long distances away by sensing low-​-frequency vibrations. 7. Explain how bony fishes differ from sharks and rays in the following: skeleton, scales, buoyancy, respiration, and reproduction.

Skeleton:​ Sharks have endoskeleton entirely cartilaginous; bony fishes have skeleton with bone of endochondral origin. Scales​: Sharks have placoid scales. Bony fishes have ganoid in ancestral form and are cycloid, ctenoid, or absent. Buoyancy:​ Sharks have no swim bladder or lung. Swim bladder usually present. Respiration: ​Sharks have 5-​-7 pairs of gills leading to exposed gill slits; no operculum. Bony fishes respiration is primarily by gills supported by arches and covered with an operculum. Reproduction: ​ Sharks reproduction involve internal fertilization. reproduction involves external fertilization.

Bony fishes'

Both have separate

sexes. 8. List four characteristics of teleosts that contributed to their incredible evolutionary diversity. 1.

Changes in jaw suspension.

2. Increased fine control of gas resorption and secretion in the swim bladder; improving control of buoyancy. 3. Homocercal tail focuses most power to the tail, allowing more speed, precise steering, protection, and social communication. 4. Use of cycloid or ctenoid scales decreased weight and increased mobility with increased feeding efficiency.


9. What morphological characteristics distinguish lobe-finned fish? Lobed muscle almost like a little arm. They have lungs to exchange gasses along with their gills so they can live in dry places. Some do don’t even have gills. They only live in South America, Australia and tropical Africa. 10. Describe discovery of living coelacanths: People were fishing in deep water in South africa and pulled some off the sea floor. They were discovered in 1938 after they were thought to be extinct. 11. Compare the swimming movements of eels with those of trout, and explain why the latter are more efficient for rapid locomotion: The eel has a serpentine swimming movement. The contractions move the full length of the body; with the amplitude of the undulation increasing as it moves towards the end of the eel. The trout is less flexible and has fewer body undulations. The fish is more built for speed than an eel. The eel is fairly efficient at low speeds, but when high speed are attempted there is too much frictional drag from the side to side movement. A trout is power loaded in the back with most of the power being delivered to the caudal fin. This results in more speed. 12. Sharks and bony fishes approach or achieve neutral buoyancy in different ways. Describe the methods evolved in each group. Why must a teleost fish adjust the gas volume in its swim bladder when it swims upward or downward? How is gas volume adjusted? To keep from sinking, sharks, which lack a swim bladder, must always keep moving forward in the water. The shark's general body design creates lift as they go through the water. The shark's head shape and shape of its tail provides this general lift. The shark also gets a little buoyancy from its very large liver that contains a fatty hydrocarbon with a density of only 0.86. Bony fishes maintain desired buoyancy by adjusting the volume of gas in its swim bladder. Because the gas volume is under such good control, the bony fishes are able to maintain almost any depth with no muscular effort. 13. What is meant by “countercurrent flow” as it applies to fish gills? Countercurrent flow:​ means that the direction of the water flow through the gills is opposite to that of the blood flow. This is the best arrangement for extracting the greatest possible amount of oxygen from the water. 14. How do Weberian ossicles increase a fish’s sensitivity to sound? Similar to bones in your ear they help sense faint sounds. Movement in the water creates a wave that hits the ossicles that create the vibration that the fish can then sense.


15.Make a cladogram that includes the following groups of fishes: chondrosteans, elasmobranchs, hagfishes, holocephalans, lampreys, lungfishes, teleosts. Add the following synapomorphies to the diagram: claspers, cranium, endochondral bone, fleshy fins, jaws, vertebrae:


16. Compare the osmotic problem and the mechanism of osmotic regulation in freshwater and marine bony fishes:​ Freshwater fishes’ bodies are hyperosmotic compared to their freshwater home. In these fish water (fresh) is always trying to move into their body and the salt in their bodies is always trying to diffuse out. Fresh water fish have two hyperosmotic regulators. First, excess water in the body is pumped out by the kidneys, which are capable of producing very dilute urine. Secondly, freshwater fishes have special salt-​-absorbing cells located in the gill epithelium that actively move sodium and chloride ions from the water back into their blood. This achieves osmotic balance in freshwater fishes. Marine fishes have the opposite problem of freshwater fishes. Marine fishes bodies are hypotonic compared to their saltwater home. These fishes bodies tend to lose water and gain salt. Marine fish need to drink the sea water to get the water it needs; then uses special salt-​-secretory cells in the gills to expel the sodium, chloride, and potassium ions back into the sea. 17.Two principal groups of fishes, with respect to feeding behavior, are the carnivores and the suspension feeders. How are these two groups adapted for their feeding behavior? Suspension eaters have a specialized filter system to filter nutrients and food out of water. Carnivorous fish have many rows of sharp little teeth that point towards the mouth to keep prey from getting away. The shape of their teeth help them hold onto prey while they twist side to side to tear off pieces. 18. How do adult Pacific salmon find their way back to their parent stream to spawn? Experiments by A.D. Hasier and others show that homing salmon are guided upstream by the characteristic odor of their parent stream. When salmon finally reach the spawning beds of their parents, they spawn and die. 19. What mode of reproduction in fishes is described by each of the following terms: Oviparous: ​ internal fertilization. Laying eggs soon after fertilization. Embryos are nourished from the egg yolk for a up to 2 years before hatching. Ovoviviparous:​ retaining developing young in the uterus, where they are nourished by the contents of their yolk sac until birth. Viviparous: ​ means that the embryos receive nourishment from the mother via a placenta or secretions from the uterus. 20.Reproduction in marine pelagic fishes and in freshwater fishes is distinctively different. How and why do they differ? Freshwater fish almost invariably produce non buoyant eggs, and generally provide no parental care. Their eggs are laid along the bottom of the water. In marine fish, males and females come together in great schools and release vast numbers of gametes into the water to drift with currents. Marine fish eggs are minute, buoyant, and transparent. Freshwater fish simply scatter their myriads of eggs among weeds or along the bottom. However, some fish such as bullhead catfish and a few darters produce


fewer, larger eggs, and their parents do provide care.

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