- Slides: 89
Fish, Sharks, & Rays
Fish Classification Kingdom Animalia Phylum Chordata (notochord or spinal cord) Subphylum Vertebrata Superclass Oseichthyes (Bony Fish)
Ichthyologists study fish.
Anatomy of Fish
Subphylum Vertebrata: Fish External Anatomy l Caudal Fin: Used to propel the fish forward. l Dorsal & Anal Fin: Stabilizers, which help keep the fish from rolling over onto its side. l Pectoral & Pelvic Fins: Paired, and help to hold the fish steady and aid in maneuvering. Also helps as brakes for stopping.
Heterocercal Tail l A type of caudal fin, usually seen in sharks, in which the upper lobe is longer than the lower one.
Homocercal Tail l A type of caudal fin, usually seen in fish, in which the upper lobe and the lower lobe are the same size.
Types of Caudal Fins Continuous Fin is able to swim in cracks & crevices.
Types of Caudal Fins Fish with lunate caudal fins tend to be the fastest fishes and maintain a rapid speed for long durations.
Types of Caudal Fins Many continuously swimming fish have forked caudal fins.
Types of Caudal Fins Fish with truncate caudal fins are usually strong, but slow, swimmers.
Types of Caudal Fins Fish with rounded caudal fins are usually strong, but slow, swimmers
Subphylum Vertebrata: Fish External Anatomy Shapes of Fish Fusiform: Foot ball shaped l Streamlined – fast swimmers (sharks & tuna) l
Subphylum Vertebrata: Fish External Anatomy l Eel shaped: Elongated (needle fish & eels)
Subphylum Vertebrata: Fish External Anatomy Spherical: Ball shaped – Inflate to avoid being eaten. (puffers & porcupine fish)
Subphylum Vertebrata: Fish External Anatomy Laterally Compressed: Their body shape is perfectly adapted for hiding in the cracks and crevices of rocks and reef. (butterfly & angel fish) l
Subphylum Vertebrata: Fish External Anatomy l. Depressed: Horizontally flat -- Fish with this : body shape spend most of their time at the bottom. They are usually camouflaged or can change color to match the bottom. We don’t mean sad… (founder & rays)
External: Barbels l A barbel on a fish is a slender, whiskerlike tactile organ near the mouth. Fish that have barbels include the catfish, the goatfish and some species of shark. They house the taste buds & are used to search for food in murky water.
Subphylum Vertebrata: Fish External Anatomy Scales: the purpose of scales if for protection Most have one of 4 types of scales l
Fish Scales Cycloid have a smooth surface. Examples: Carp & Salmon.
Fish Scales Ctenoid have teeth along the edge and are rough to the touch. Examples: Bass, Bluegill & Perch.
Fish Scales Placoid look like tiny teeth or thorns and feel like rough sandpaper. Examples: Sharks & Rays.
Fish Scales Ganoid are hard, interlocking, and diamond-shaped. Example: Gar
Subphylum Vertebrata: Fish External Anatomy l Fish are covered by a protective transparent skin, which produces a lubricating mucous. l The mucous helps the fish move through the water.
Subphylum Vertebrata: Fish Internal Anatomy Buoyancy l The swim bladder is a thin-walled sac that can inflate or deflate when the gases from the blood pass into or out of it. l This helps the fish move up and down in the water column.
Problems w/ swim bladder • If pulled up too fast, the swim bladder over expands & can’t deflate. • Makes releasing fish difficult. • Use a needle to deflate. Air Bladder
Subphylum Vertebrata: Fish Internal Anatomy Buoyancy l Sharks do NOT have swim bladders! l They have very large livers filled with oil, which is less dense than water. l Constant swimming and lift from the flow of water over the shark’s lateral fins help prevent it from sinking.
Subphylum Vertebrata: Fish Internal Anatomy Senses l Have all 5 senses and one more – a 6 th sense l Sensory organs called the lateral line system alert the fish to movement of other organisms around them and changes in the water like pressure and currents.
Subphylum Vertebrata: Fish Internal Anatomy Breathing l Fish have gills to obtain oxygen and give off carbon dioxide. l Fish have an outer covering called the operculum that protects the feathery gills. l Fish have a 2 chambered heart
Subphylum Vertebrata: Fish Internal Anatomy l Sharks have gill slits. l Most sharks have to continuously swim to force water over gills.
Fish Reproduction Catadromous: Fish that live mostly in fresh, and breed in saltwater. (Example: American Eel)
Fish Reproduction Anadromous: Fish that live mostly in saltwater, and breed in freshwater. (Example: Salmon)
Fish Reproduction Oviparous: Refers to animals whose eggs hatch outside the mother’s body. Sharks & Ray Eggs Fish Eggs
People Eat Fish Eggs! People eat Caviar which are fish eggs typically from sturgeon fish who are found in the Great Lakes! 1 oz can cost $90 or more!
Fish Reproduction Ovoviviparous: Refers to animals whose young are born alive after developing in eggs inside the mother’s body. (Mostly a shark behavior)
Ovoviviparous l Oophagy: The practice of embryos feeding on eggs produced by the ovary while still in the uterus. (Example: short fin mako) Intrauterine Cannibalism: The first developed embryo consumes both developing eggs & and developed embryos. (Example: grey nurse shark) l
Fish Reproduction l Most fish are egg-layers, but many bear living young. Live-bearing fish may be ovoviviparous or viviparous. l These fish are more difficult to fish farm because the breeding conditions are specific. l
Fish Reproduction Viviparous: Refers to animals that bear live young that are nourished directly by the mother’s body as they develop.
Fish Reproduction l Male live-bearers have an organ called the gonopodium for internal fertilization.
Fish Farms Aquaculture: Fish farming of fresh water fish. Mariculture: Fish farming of marine fish. Oviparous fish are easy to produce fry because the eggs & sperm can be taken, and fertilized in mass quantities.
Fish Farms l Demands on wild fisheries by commercial fishing operations have caused widespread overfishing. l Fish farming offers an alternative solution to the increasing market demand for fish & fish protein.
Fish Farming l Fish species raised by fish farms include salmon, catfish, tilapia, cod, carp, & trout. l Fish farms are criticized for pollution problems, use of antibiotics, use of genetic engineering, and concerns of escaping fish becoming invasive species.
Unusual Breeders l Mouthbreeders: Carry their fertilized eggs in their mouths until the young can cope with life. l Incubating the eggs usually falls to the males. l Male tilapia holds the eggs in his mouth until they hatch. If the babies don’t scatter, he will eat them.
Mouthbreeders l Female malawi fish goes one step further, allowing her babies to hide in her mouth in the event of danger.
Unusual Breeders l Pouchbreeders: Carries their fertilized eggs in a pouch. l Female seahorse lay her eggs in his brood pouch, and the eggs develop for 2 -6 weeks until they are fully formed. He then shoots out the babies from his pouch. *No sound*
Unusual Breeders l Nesting: Birds aren’t the only animals to build a nest. Bubble Nest l The male betta will blow an elaborate bubble nest when he is ready to spawn. The male will continue to tend the bubblenest, spitting eggs that fall out back into the nest.
Unusual Breeders l Fatal Breeding: After breeding, they die. Example: Salmon Eggs & Sperm Mixing
Unusual Breeders l Pacific salmon are born in freshwater, migrate to saltwater. To breed, they return to the same place they were born by swimming up stream & leaping over waterfalls. Once they spawn, they die shortly after.
Unusual Breeders l Simultaneous Hermaphroditic: A single fish is both male & female. ADVANTAGE: -- Deep sea: low population density = few potential mates
Unusual Breeders l Sequential Hermaphrodite: (Sex reversal) -- Change from being males to females (Example: anemone fish) -- Change from being females to males (Example: wrasses & parrot fish)
Protection Video l Camouflage: Many fish have colors or patterns that match their backgrounds. Some fish can even change color to match different backgrounds either to hide from prey (if an ambush is planned!) or to hide from a predator. Flounder! Fish
Protection l Countershading: Many fish are dark on top and light on the bottom. When seen from above they "disappear" by blending in with the dark color of the depths of the bottom. Seen from below, the light belly blends into the sky above. No…this is not a fish, but shows… Countershading
Why School? l Protects fish from enemies. l It is also believed that swimming close together reduces friction and allows fish to conserve energy when swimming.
Why School? l Having 50 sets of eyes and noses gives the school a better chance of finding dinner. l When fish spawn a school ensures that at least some eggs will elude predators due to the sheer numbers produced in a large group.
Protection l Eye Spots: Are a form of mimicry. The eye spot, usually found near the tail, may be used to draw attention away from the real eye which is a target that a predator might strike.
Protection l Warning Coloration: Many fish use bright colors to "advertise" the presence of venomous spines or some other defensive mechanism. l Common warning colors: Red, Black, & Yellow
Protection l Stingray Barb: Located at the base of the sting ray’s tail. It injects venom from a gland through a groove in the spine. l Beach goers should do the “stingray” shuffle to avoid getting a barb in the foot.
Protection l The serrated edges make it difficult to pull the barb out. l The spine also introduces bacteria.
Jobs: Cleaning Stations l As fish approach the cleaning station they adopt a cleaning posture. l This posture varies between species; it may be nose down, nose up or slightly on one side. The point is that the cleaner fish recognizes this posture as a message to “come clean me”
Job: Cleaning Station l The cleaner then moves in and pecks away at parasites and dead skin to give its client a general clean up Video
Job: Cleaning Station l It isn't just the outside that gets cleaned. The cleaner will even enter a client's gills and mouth.
Sharks Kingdom Animalia Phylum Chordata Subphylum Vertebrata Class Chondrichthyes (Cartilaginous Fish)
Extra Sense l Ampullae of Lorenzini are special sensing organs, forming a network of jelly-filled canals. l Are capable of detecting the electrical fields generated by moving animals
Teeth l A single shark can go through about 50, 000 teeth in a life time. l Have a conveyor belt of teeth. When one is lost, a new one rotates up to take its place. l Each tooth shape has a different function.
Male & Female Sharks l Males have claspers – Sperm transfer organs l Females don’t have claspers Male Shark Female Shark
Mating l Male sharks bite the female’s pectoral fin during mating.
Sharks have a “Cancer Shield” l It was once thought that sharks never get cancer. l They do get cancer, but very seldom. l Sharks injected with carcinogens, have detoxified these pathogens and survived apparently without ill effects. l Scientists have been researching the shark’s ability to prevent cancer to help humans fight cancer. l Shark liver oil and shark cartilage is believed to cure cancer, but this is NOT true!
Sharks as Villains!
Villains l Jaws (1975) is a realistic science-fiction suspense/horror film that taps into the most primal of human fears – what unseen creature lurks below the dark surface of the water. l Have a bad reputation for being bloodthirsty mankillers because of Jaws. A rampaging shark killing everyone it could find is completely unrealistic! l
Villains l Most shark attacks are accidental & rarely end in fatalities. l There around 50 -75 shark attacks every year WORLDWIDE. Only 8 -10 end in fatalities. l Sharks can go days or weeks before eating again. l Great white, tiger, and bull sharks are the most prone to attack humans.
Villains? l Reasons for attacking: Territorial, mistaken identity, & breeding season. Some sharks even warn before attacking with an arched back posture (similar to a cat).
How to Avoid a Shark Attack l When swimming at a beach, stay in a group and do not go too far from the shore. l Avoid being in the water during the hours of twilight, early morning, and darkness, when sharks are most active. l Stay out of the water if you are bleeding. l Do not enter the water wearing shiny jewelry or bright clothing. l Avoid areas being used by fishermen, especially if you see diving birds or other signs of bait fishes and feeding activity. l Exercise caution when entering murky waters and areas near sandbars or steep drop-offs. l Do not enter the water if sharks are known to be present, and evacuate the water if you see a shark.
Victims l Not only are sharks fished for their meat, fins or cartilage, millions of them die needlessly as undesirable bycatch in nets & longlines. l A study in 1991, found that out of 8. 3 million sharks that were caught, more then 87% were thrown back…dead.
Shark Finning is the cutting off of the fins, and throwing the body back into the ocean. l l The rest of the body could also be used, but is wasted!
Shark Finning l Reason: Shark Fin Soup – A very expensive dish l Price runs between $100 -$400 per bowl! l Disney World in Hong Kong is in hot water – They had plans of adding shark Fin Soup to their menu, but is facing opposition.
Searching for Solutions l The new tools include electronic beach shields and chemical repellents. l Researchers have been extracting certain chemicals out of these dead carcasses, purifying them and testing them on sharks. It works very well. l Ironically, this technology not only saves humans from sharks, but sharks from humans.
Rays & Skates
Rays & Skates l Characterized by their flattened shape and long, spine-bearing tails, stingrays are unique and cartilaginous cousins of the sharks. l Stingrays have pectoral fins that are fused to the sides of their rostrum or "head. "
Rays & Skates l External gill openings are located on the stingray's ventral side or "underside. " l Benthic rays, such as the Atlantic stingray, are often found buried in the sand. l Benthic: Associated with the seafloor. l They usually have a rounded or "diamond-shaped" body and their stings, when present, are located near the middle or lower third of their "tail. " As mostly bottom feeders, these rays generally feed on worms, clams, shrimp, crabs, snails and occasionally fish.
Rays & Skates l Spiracles are small openings on the surface of some sharks, all rays & skates that lead to the respiratory system. l Is found behind each eye, and is often used to pump water through the gills while the animal is at rest. l Helps rays breath while buried in the sand.
Rays & Skates l Pelagic rays, like the spotted eagle ray and manta ray above, are more active swimmers that have a "bat-like" shape. l Pelagic: Open water column.
Difference Between Rays & Skates l Skates are a type of "ray" that differ considerably from stingrays. l Skates, such as the clearnose skate, do not possess venomous barbs like stingrays although many do have sharp thorns located on their dorsal surface and tails.
Differences Between Rays & Skates l Also, unlike stingrays, skates primarily live in marine habitats and rarely enter brackish or freshwater environments. l The most prominent difference between the two groups is that all stingrays give birth to live young while skates reproduce by laying eggs in leathery capsules sometimes called mermaid's purses.
All characters in Finding Nemo are real-life fish!