Presentation on theme: "Shark! Marine Biology - Conrad. Superclass Agnatha The first chordates with a notochord. This lovely looking, fish- like organism is jawless and lack."— Presentation transcript:
Shark! Marine Biology - Conrad
Superclass Agnatha The first chordates with a notochord. This lovely looking, fish- like organism is jawless and lack most fins. They are parasites on fish. They are called hagfish or lamprays belonging to class agnatha. Image courtesy of Florida Museum of Natural History. Retrieved on 1/8/07 from
Class Chondrichthyes: Sharks and Rays Skeletons composed of cartilage. Sharks have jaws of replaceable rows of teeth to injure prey. Gill slits lack operculum (covering). Sharks have tiny scales, electric sensors, and internal fertilization. The tail/fin design and large, oily liver provides buoyancy. Osmosis is controlled through the urea concentration in the blood. The spiral intestine increases SA. Image courtesy of Florida Museum of Natural History. Retrieved on 1/8/07 from
Class Chondrichthyes: sharks, rays, skates, and ratfish Rays have flat teeth and are bottom eaters. Hide in sand. Barb on tail for defense. Since their mouth is ventral they need to take in water from spiracles (gill openings) that are located on their dorsal surface to avoid breathing mud. Was is released through gill slits near the mouth. Image courtesy of Florida Museum of Natural History. Retrieved on 1/8/07 from
Shark attack Only 12 of the 375 species of sharks have ever attacked humans. 50 attacks world wide per year. Watch out for the tiger, bull, and great whites. –Stay in groups –Stay close to shore, but away from drop offs (they hide there) –Stay out of cloudy water or night (they are nocturnal). –Avoid swimming when bleeding (distinct smell (olfactory) –Avoid shiny jewelry (resembles fish scale shine). –Avoid fishy areas used for fishing or diving birds. –Avoid bright clothing because they are keen to contrast. –Avoid splashing and pet movements. Stay calm when shark arises. Move away from it and towards shore.
Sharks attack each other too! Here is the cookie-cutter shark. Its round jaws attach with great suction, twist, and pull out a chunk of flesh.
Sensory Structures Sharks are far sighted, but otherwise see like us (color and focus). They also have a tapetum lucidum to reflect additional light. A nictitating membrane is a clear eyelid to protect their eye. A cartilaginous tongue, called a basihyal, is used to tear food. Taste buds are on the papillae of the mouth. Sharks have ears and lateral lines that detect vibrations in the water The ampullae of Lorenzini on their chin sense electrical impulses from the muscles of prey and for navigation. Sharks have excellent smell (olfactory senses) in their nostrils. Eels are fish that use electric sensors to communicate to each other, locate prey, and to navigate. Eels also generate electricity to communicate, zap their prey, and for defense.
Shark Swimming Sharks lack a swim bladder so they need a lighter skeleton, oils, and tail/pectoral fin design to prevent sinking. The dorsal, anal, and pelvic fins maintain balance. The caudal fin (tail) creates lift and pushes fin through the water. Image courtesy of Florida Museum of Natural History. Retrieved on 1/8/07 from
Shark Reproduction Male sharks have claspers for internal fertilization Sharks may be oviparous (lay eggs) or Viviperous gestate eggs either maternally or using a yolk sack inside the mother giving live birth. The hard (horny material?) egg case of sharks, rays, or skates is called a mermaids purse, which contains the developing embryo enough yolk to sustain the nutritional needs of the embryo until it hatches. The corner tendrils wrap around rocks or kelp for anchor. If 2 sharks share the same yolk, one will eat the other (adelphophagy Image courtesy of encarta-msn (2007 and the Florida Museum of Natural History. Retrieved on 1/8/07 from
Shark Facts quoted from Existing for 400 million years, sharks came before dinosaurs! These good survivors have not evolved in the last 150 million years. Sharks have the most powerful jaws on the planet. Unlike most animals' jaws, both the upper and lower jaws move. Each type of shark has a different shaped tooth depending on their diet (sharp, pointy teeth for carnivores!). They go through over 20,000 teeth in a lifetime! Even their skin is made of small, teeth (denticles) instead of ordinary fish scales. They are hydrodynamic, and feel like sand paper. They protect the shark from injury. Great whites can detect one drop of blood in 25 gallons (100 liters) of water and can sense even tiny amounts of blood in the water up to 3 miles (5 kilometers) away. They have 3,000 serrated teeth!
Nice Sharks Harmless sharks tend to be the largest! The 1. basking shark, 2. whale shark, and 3. megamouth sharks eat plankton by swimming forward with their mouths wide open. "Gill rakers" at the back of their throat strain the food from water. Quoted from
Swim or Die. Sharks have to force water over their gills in order to breathe. Gas exchange is better the faster the faster the shark moves "ramjet principle forces more gas into the water. Some sharks have to keep moving to breathe. If they stop they die from suffocation (this accounts for the majority of the big predators caught in beach-defense nets being brought up dead). Some bottom dwelling species (dogfish, carpet, and nurse sharks), can stay docile (lazy), because they pump water by rhythmically contracting the muscles that control the inlet and outlet valves of the gill system. The Tiger shark and the Grey Nurse Shark are able to make use of both pumping and ramjet, achieving a real saving in energy. Nurse sharks use this pump to create a strong suction for feeding on conch. Nurse Shark
Shark Blood To ensure a good transfer of oxygen from the gills to the muscles and other organs, a maximum percentage of red corpuscles in the blood (haematocrit) is needed. A final parameter for good oxygen transfer is the cardiac pump. Larger sharks have larger hearts. Sharks have only 2 chambers in their heart. The image of the aortas leaving the sharks heart.
Mean Sharks The most dangerous sharks are the 1. Great White shark, 2. Tiger shark, 3. Hammerhead shark, 4. Mako shark, and 5. Bull shark. There are only about 100 shark attacks each year and only 10 of those result in a human death. However, people kill thousands of sharks a year for sport and food
To a shark, a surfer paddling on a surfboard can look a lot like its typical prey.
Dangerous Sharks Great White: cool, coastal waters. They are endangered due to over-fishing (no food), net by-catch, and hunting. They are 20ft. Long. Tiger shark: identified by dark, vertical stripes found on juveniles. They do not have a picky palate, so the are not likely to swim away after biting a human, as great whites do. They have excellent senses of sight and smell. Strong jaws can crack turtle shells. Stomach contents may include license plates and old tires. They are heavily harvested for their fins, skin, and flesh, and their livers contain high levels of vitamin A. Their repopulation rates is very low. Bull Shark: can go into fresh water and beaches. Nurse Sharks: are nocturnal. Docile during the day, but will attack when bothered. Bulldog jaw.
The Maugean Skate
Ventral cut to remove the lobed liver, vertebrae, and egg cases in this female.
Fish - Class Osteichthyes Bony endoskeleton Excellent sense of smell but not eyesight Swim bladder Operculum Scales Pyloric cecum Paired ray fins* Lateral line 2 chambered heart Cold blooded * one living specie has lobed fins Image courtesy of National Geographic (2006).
Fins and Swimming The air filled swim bladder prevents sinking. Fins are lobed or spiny. Rigid, streamlined body shape to be pushed through the water using myomer muscle contractions and fins (caudal fin). Caudal fin: Tail fin. Forked tail for speed; flat tail for speed quick bursts of speed; and round tails are slow swimmers. Pectoral fins turn and stop and other fins are for balance. Image courtesy of Florida Museum of Natural History. Retrieved on 1/8/07 from
External Anatomy of Bony Fish Image courtesy of Florida Museum of Natural History. Retrieved on 1/8/07 from
Fish Skin Fish scales provide protection and calcium storage. Growth rings. scales: ganoid, cycloid, placoid & ctenoid Fish are covered in large scales that are covered by mucus/slime. The slime coat prevents infection and skin can be used for excretion, breathing, and regulating osmoregulation. Melanophores add dark color, chromatophores add light color, and iridophores add iridescence by having tiny crystals inside the cell. Image courtesy of Mills (2000). Im Hot! Parrotfish make their own sleeping bag out of mucous. Image courtesy of Lauterman (2005).
Coloration 1. Camoflague with colored pigment cells. 2. Disruptive patterns break up and disguise their outline (cryptic coloring). 3. Counter shading is dark on top and light on bottom. When looking up the water appears light like their underside, but looking down they blend into the dark. 4.Bright colors to warn Im poisonous or Ladies come and get me. A. B. C. D. Image courtesy of Florida Museum of Natural History. Retrieved on 1/8/07 from
Other Tricks Cryptic coloring with light breaks up silhouette in deep sea fish using bioluminescent bacteria or photophore cells. Deep Sea anglers use the light to lure prey or mates. Stingrays, catfish, and others may have stinging spikes with venom (but dont kill humans). Barbles are used to feel and sort food. Image courtesy of Florida Museum of Natural History. Retrieved on 1/8/07 from
Feeding Phillips (2006) jeb.biologists.org/cgi/content/full/209/14/iii Fish do not chew, but pharyngeal teeth and tongue can grind. They have taste buds. Teeth are used to hold onto food Food is sucked into the mouth when the operculum (gill covering) is closed.
Mouth Morphology Determined by Diet Image courtesy of Castro and Huber (2000). Surface Feeder (insects) Downward mouth: benthic feeding scavengers Break off pieces of coral. Their poop makes the coral sand. Terminal: feed at all levels and variety foods. carnivorous fish have strong suction and closes using teeth to hold prey.
Fish Digestive System Fish eat a variety of foods because they can not produce their own amino acids. The stomach stores large infrequent meals, grinds, and chemically digests food with enzymes. The pancreas and small int. make enzymes too. Bile from the liver digests oils (other human functions). The small intestine has pyloric ceca pouches to increase surface area for absorption. The large intestine reabsorbs water and vitamins Some fish lack a stomach (parasites). Undigested food exits the anus. Images courtesy of High Country Sailing (2006).
Gas Exchange in Fish The 2 chambered heart pumps blood to the gills. Blood flows through the gills in the opposite direction of the water (countercurrent) to maximize gas exchange. The gills pick up oxygen and emit CO 2 by way of diffusion. Water has less dissolved oxygen than air especially warmer water. Oxygen binds to the hemoglobin in blood and is carried to the cells. The closed circulatory system (blood) transports and exchanges waste, food, and gases throughout the body.
Gill Mechanisms The gills are contained within a common chamber that is covered with an operculum. Water is sucked in when the mouth opens and operculum closes. When the mouth closes the water is forced over the gills and through the operculum. This can also be used to swim faster. Gill arches of cartilage support the gill fillaments. There are many rows of feathery filaments with blood containing lamellae to increase SA. Gill rakers rake debris from the gills and can filter feed. Gills are cleaned with cilia and mucous located on their surface
Chordate Species Images courtesy of Miller and Harley (1996).
Fish Excretion Marine fish are osmoregulators that excrete salty urine. They drink a lot of water and their kidneys pull out the salts and save the water. Chloride cells in the gills help remove salt and waste. Kidneys are also used to make blood cells and hormones.
Fish Nervous System and Senses They have a brain and can sense pain. They can remember/make mental images. Eyes focus differently and they lack lids. Fish can hear vibrations with their lateral line and create sounds with their swim bladder.
Reproduction Fertilization can be internal or external. Some can store sperm for months. Some males will turn into females if absent. Some males are small parasites on females. Some females produce males or sometimes eat them. If a male with a harem dies, the largest female undergoes gender reassignment. Some fish are born males and mature into females. Some lay eggs randomly or in layers on rocks. Some form bubble nests of saliva or hold onto them in brood pouches. Some nests are guarded.
Ladies! Theres no need to fight! Image courtesy of Murch (2006).
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