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Fish, Sharks, & Rays. Fish Classification. Kingdom Animalia Phylum Chordata (notochord or spinal cord) Subphylum Vertebrata Superclass Osteichthyes (Bony Fish). Ichthyologists study fish. Anatomy of Fish. Fish External Anatomy.
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Fish Classification Kingdom Animalia Phylum Chordata (notochord or spinal cord) Subphylum Vertebrata Superclass Osteichthyes (Bony Fish)
Fish External Anatomy • Caudal Fin: Used to propel the fish forward. • Dorsal & Anal Fin: Stabilizers, which help keep the fish from rolling over onto its side. • Pectoral & Pelvic Fins: Paired, and help to hold the fish steady and aid in maneuvering. Also helps as brakes for stopping.
Heterocercal Tail • A type of caudal fin, usually seen in sharks, in which the upper lobe is longer than the lower one.
Homocercal Tail • 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
Fish External Anatomy Shapes of Fish • Fusiform: Foot ball shaped • Streamlined – fast swimmers (sharks & tuna)
Subphylum Vertebrata: FishExternal Anatomy • Eel shaped: Elongated (needle fish & eels)
Subphylum Vertebrata: FishExternal Anatomy Spherical: Ball shaped – Inflate to avoid being eaten. (puffers & porcupine fish)
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)
Fish External Anatomy • 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. (founder & rays)
Subphylum Vertebrata: FishExternal Anatomy • Scales: the purpose of scales if for protection Most have one of 4 types of scales
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
External: Barbels • 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.
Fish External Anatomy • Fish are covered by a protective transparent skin, which produces a lubricating mucous. • The mucous helps the fish move through the water.
Fish Internal Anatomy Buoyancy • 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. • This helps the fish move up and down in the water column.
Fish Internal Anatomy Buoyancy • Sharks do NOT have swim bladders! • They have very large livers filled with oil, which is less dense than water. • Constant swimming and lift from the flow of water over the shark’s lateral fins help prevent it from sinking.
Fish Internal Anatomy Senses • Have all 5 senses and one more – a 6th sense • 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.
Internal Anatomy Breathing • Fish have gills to obtain oxygen and give off carbon dioxide. • Fish have an outer covering called the operculum that protects the feathery gills. • Fish have a 2 chambered heart
Internal Anatomy • Sharks have gill slits. • 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. Fish Eggs Sharks & Ray Eggs
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 • 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)
Fish Reproduction Viviparous: Refers to animals that bear live young that are nourished directly by the mother’s body as they develop.
Fish Reproduction • Most fish are egg-layers, but many bear living young. Live-bearing fish may be ovoviviparous or viviparous. • These fish are more difficult to fish farm because the breeding conditions are specific.
Fish Reproduction • Male live-bearers have an organ called the gonopodium for internal fertilization.
Unusual Breeders • Mouthbreeders: Carry their fertilized eggs in their mouths until the young can cope with life. • Incubating the eggs usually falls to the males. • Male tilapia holds the eggs in his mouth until they hatch. If the babies don’t scatter, he will eat them.
Unusual Breeders • Pouchbreeders: Carries their fertilized eggs in a pouch. • 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.
Unusual Breeders • Nesting: Birds arent the only animals to build a nest. • 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. Bubble Nest
Unusual Breeders • Fatal Breeding: After breeding, they die. Example: Salmon
Unusual Breeders • 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 • Simultaneous Hermaphroditic: A single fish is both male & female. ADVANTAGE: -- Deep sea: low population density = few potential mates
Unusual Breeders • Sequential Hermaphrodite: (Sex reversal) -- Change from being males to females (Example: anemone fish) -- Change from being females to males (Example: wrasses & parrot fish)
Protection • 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.
Protection • 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.
Why School? • Protects fish from enemies. • It is also believed that swimming close together reduces friction and allows fish to conserve energy when swimming.
Why School? • Having 50 sets of eyes and noses gives the school a better chance of finding dinner. • When fish spawn a school ensures that at least some eggs will elude predators due to the sheer numbers produced in a large group.
