Jawless, Cartilaginous, and Bony

Jawless Most primitive type of fish living today Lack jaws Feed by suction with the aide of a round, muscular mouth and rows of teeth Body type- cylindrical and elongated like a snake or eel

Jawless Fish- Hagfish Also known as slime eels Feed mostly on dead or dying fish Can dig into their prey and eat them from the inside out Live in burrows that they dig into muddy bottoms Live in cold water

Jawless Fish- Lamprey Live in temperate regions Primarily freshwater fish Breed in rivers and lakes but move to the sea as adults Attach to other fishes and suck their blood Type of parasite Also feed on bottom invertebrates Ex. clams, worms

Cartilaginous Have a skeleton made of cartilage Cartilage: material that is lighter and more flexible than bone Includes sharks, rays, skates, and ratfishes Have movable jaws that have well-developed teeth Mouth is almost always underneath the head Have paired fins for efficient swimming Have placoid scales  scales that have a pointed tip that are directed towards the back Gives cartilaginous fish their rough, sandpaper skin

Cartilaginous Fish- Sharks Adapted for fast swimming and attacking prey Have a spindle-shaped body  rounded in the middle and then gets slimmer towards each end Heterocercal tail- upper part of the tail is longer than the bottom part 5 to 7 gill slits located behind their head on each side

Sharks cont. Have powerful jaws Contain rows of sharp, triangle shaped teeth If a tooth is lost, the tooth behind it shifts forward to replace it Found all throughout the ocean Seen more in tropical, coastal waters Smallest species- spined pygmy shark Largest species- whale shark

Spined pygmy shark Whale shark

Thresher shark Nurse shark Bull shark

Cartilaginous Fish- Rays & Skates Have flattened bodies like a pancake Mainly live on the bottom of the ocean Gill slits located on their bellies Side fins are flat and expanded Look like wings Side fins attached to their heads Eyes are located on top of their head

Rays & Skates cont. Rays have a whip-like tail Usually has stinging spines at the end of it for defense Like to cover themselves with sand Feed on clams, crabs, small fishes, and other small animals living in the sediment “Fly” through the water using their side fins as wings Skates lack a whip-like tail Breeding: Skates- lay egg cases  mermaid’s purse Rays- give birth to live young

Skate Manta ray Stingray

Cartilaginous Fish- Ratfishes Have only 1 pair of gill slits covered by a flap of skin Feed on bottom-dwelling crabs and clams Can have a long rat-like tail

Bony Have skeletons made of bone Have cycloid scales  smooth, thin, flexible, and overlapping Presence of an operculum/gill cover  a flap of bony plates and tissue that protects the gills Homocercal tail- upper and lower part of the tail fins are the same size

Bony cont. Mouth is located at the end of their bodies Jaws are able to move and stick outward from their mouths Contain a swim bladder- a gas-filled sac located above the stomach and small intestine Prevents fish from sinking or rising

Body Shape, Coloration, Swimming, Feeding, Breathing, Sensory Organs, Behavior

Body Shape Body shape is directly related to the fish’s lifestyle Streamlined- swim fast through the water Squished in on the sides- casually swim around reefs and kelp beds but can still swim away fast when needed Flat- lay on the bottom Ribbon- live in narrow spaces Squished in on sides

Streamlined Flat Ribbon

Coloration Bright colored = lives in tropical water Chromatophores: special cells in the skin that give bony fish their different colors Colors can tell: Mood If ready to mate Dangerous Poisonous Taste bad

Disruptive coloration: color stripes, bars, or spots that break up the outline of the fish Countershading: have a silver or white belly and a dark back Common in open-water fish and shallow-water predators

Swimming Swim to get food, escape from predators, and find mates Many cartilaginous fish and some body fish must swim to get water over their gills to get oxygen Swim in a side-to-side motion of the body or tail Many bony fish swim by moving their different fins Tails are used as a rudder  determines which direction fish will go

Bony fish can also use their fins to: Hover over the bottom to hunt for food Glide/fly through the water Crawl or rest on the bottom

Feeding Most sharks are carnivores  use jaws to take bites of their prey Can also be filter feeders  take in water over their gills to filter out plankton to eat Can suck plankton and small fish into mouth Most bony fish are carnivores Shape of mouth determines type of prey Mouths contain well-developed teeth Deep-water fish can swallow prey bigger than themselves

Can also be grazers  feed mostly on seaweeds and plants Use teeth to scrape algae off rocks Can also filter feed  take in sediment through their mouths to filter out the plankton then release excess sediment through their gills

Breathing Fish get oxygen by taking in water through their gills that has dissolved oxygen in it Release carbon dioxide from their blood through their gills Need to make sure that water always flows over their gills to get oxygen by swimming Sharks need to swim continuously Opening and closing of their mouths also forces water over their gills

Breathing cont. Spiracles: a pair of round openings behind each eye Located on the backs of skates and rays Allows them to breathe even when they’re buried in sediment

Behavior Territoriality: fish establish home areas that they defend against intruders Used for feeding, resting, and breeding Aggressive behaviors to defend their territory: Raised fins Open mouth Fast darting around Grind teeth Pull muscles of swim bladder to make a drum sound

Behavior cont. Schooling: many fish form well-defined groups that they live and travel in Function as a coordinated group without a defined leader Offers protection against predators Increases swimming efficiency  reduces water resistance Helps with feeding and mating

Behavior cont. Migration: regular mass movement from one place to another once a day, year, or lifetime Reasons: Feeding  go to place with more food Ex. tuna Reproduction  go to a different place to mate and lay their eggs Ex. salmon