Slide 1 Kingdom Animalia • Phylum Chordata • Subphylum Vertebrata • All vertebrates share the following fundamental characteristics: • A backbone called a vertebral column • Nerve cord or spinal cord • Bilateral symmetry • Endoskeleton • The Vertebrates include Fish, Amphibians, Reptiles, Birds and Mammals. • Marine Fish • They live and grow in water, swim with fins, and use gills for oxygen • and carbon dioxide exchange • They are cold blooded- meaning their body temperature is regulated by the temperature of the environment. • There are three different Classes that include marine fish
1. Class Agnatha – Jawless Fish The most primitive of any of the types of fish They lack jaws They lack paired fins The only two species in this class: Hagfish Hagfish are entirely marine, benthic scavengers that secrete a thick slime from glands in their skin to protect them from predators They can tie their body in a sliding knot to clean their body of excess slime or help tear food apart Lampreys Lampreys are anadromous meaning that the fish will move from a marine environment to a freshwater for spawning They are parasitic using hook shaped teeth within their oral disc (mouth)
2. Class Chondrichthyes (Sharks, Rays, & Chimaeras) • Most of the fish in this class are marine. • They obtain an osmotic balance with their marine environment due to high concentrations of Urea and TMAO( product in the body that protects proteins from high salt concentrations) • Urea is produced in the liver and is a toxic nitrogen containing waste by-product • The species in this class are know as Cartilaginous Fish, due to the lack of bone material for their skeleton. • Most members of this class can live for long periods of time • They have paired fins and biting jaws with teeth. • Most sharks are fast moving pelagic predators. • Most rays are bottom dwelling. • There are three body shapes in this class: • Streamlined Dorsoventrally Flattened Unusual • Sharks Rays Chimaeras
Sharks • Have a relatively small brain. The large Olfactory Lobe of the brain is important for their acute sense of smell. The olfactory lobe connects to the nostrils of the shark • Water is taken in through the mouth of the shark. Contraction of throat muscles pulls the water in further and the water moves over the tongue and across the gills on either side of the throat. Gill Rakers on the inner side of the gills prevents foreign objects from clogging the gills. Oxygen is then pulled out of the water and into the circulatory system. The rest of the water is pumped out of the gill area through the Gill Slits on the side of the sharks head. • The oxygen in the blood is them carried to the small Heart located near the base of the gills and from there it goes to the rest of the body.
Sharks are torpedo shaped. Their tail is used for propulsion. They have 2 dorsal fins and all of the fins have cartilage supporting them. Claspers are used for reproduction. The skin of sharks is covered by a protective layer of scales called Placoid Scales. They are also called denticles. These scales have a small tooth like projection and gives the skin a sand paper type of texture. The spiracle is remnant of a gill slit. The gill slits are where the water comes out with the carbon dioxide wastes.
The Liver functions to store surplus nutrients for the body and detoxify certain substances. • The liver also helps the shark to maintain buoyancy in the water. • The liver stores oils which are less dense than water so the liver in sharks is larger than that of other types of fish (bony). • Sharks and rays in this class require forward motion to keep from sinking.
The stomach and intestines vary in length due to the diet. • Sharks have a Spiral Valve and it serves to increase the surface area of the intestine to be able to absorb nutrients into the blood stream for use throughout the body.
The stomach and intestines vary in length due to the diet. Sharks have a Spiral Valve and it serves to increase the surface area of the intestine to be able to absorb nutrients into the blood stream for use throughout the body. The Kidneys help regulate or balance the blood chemistry ( all the chemicals found in the blood) waste products are passed through an urogenital opening. Shark skeleton is flexible with fewer joints; therefore, the body is less maneuverable. The skeleton is made of cartilage, not bone. Cartilage is a tough, elastic connective tissue. The claspers on the males are inserted into the female and sperm passes along a groove into the female. Some sharks lay eggs in a leathery case. Others have young develop inside the female. No sharks care for their young after hatching.
Sting-Rays, Manta Rays, Eagle Rays and Skates are cartilaginous fish. They have flat bodies and wing like pectoral fins that are attached to the head. Since Skates and Rays are bottom dwelling, if they tried to take in water through their mouth they could choke because they would take in sand at the same time. The spiracles located near their eyes are for taking in water. Water passes over the gills and then comes out of the gill slits located on the underneath side of them. Skates are harmless, bottom dwelling fish. Their diet is shellfish, worms and crabs; they have strong jaws that can easily crush the shells. Male skates have claspers and females produce a leathery egg case that hooks onto seaweed. Empty egg cases are called Mermaid’s purses.
Sting Rays and Sawfish Sting Rays are similar to Skates, but they have a long whip like tail with a stiff spine or barb. The spine is used for defense. Venom is released from the spine which is painful but not fatal. Sting rays give birth to live young. Sawfish is a shark like ray found in warm waters. The sawfish slashes through schools of fish with its saw-like nose eating those fish that he injured. Sawfish do not have a stinging barb (spine).
3. Class Osteichthyes – Bony Fish • More than 95 % of the fish on earth belong to this class • They have a skeleton that is made up of bone • They can be found in every type of aquatic environment (lakes, rivers, oceans) • They have a protective covering of scales which grow from the skin and are loosely attached to the skin • As a fish grows a new growth layer is added to the scale, a fish can be aged by the number of growth rings on a scale • There are many different types of scales The skin also secretes a slimy mucus over the scales which acts as a barrier against infection and reduces the amount of friction as the fish moves through the water.
The color of fish is due to chromatophores (pigment cells) and iridocytes (reflective cells) in the skin. • The Lateral Line in a fish is made up of sensory cells that help the fish detect changes in the water. • In bony fish the gills are covered by a flap of bony tissue called the operculum. The operculum open and closes every time the fish breathes. • Like the shark, when a fish breathes water is pulled in through the mouth and passes over the blood filled gills oxygen then diffuses (passes) from the water through the gill membranes and into the blood of the fish carbon dioxide diffuses out of the gills and back out into the water
Feeding Behavior in bony fish varies greatly and can be observed with different mouth types. Attackers- jaws with long sharp teeth for seizing and holding prey Pickers- stout jaws with protruding teeth for crushing a variety of food Probing & Sucking- have tube-like snouts & small mouths Grazers- have fused teeth with a sharp cutting edge used for scraping Grubbers- will blow jets of water into the ocean bottom or have barbels that hang from their lower jaw which will move over the ocean bottom finding food
Swim Bladder is a gas filled sac that the fish can inflate or deflate to maintain buoyancy or its ability to float or rise in the water. Neutral buoyancy is the ability to maintain a steady position in the water, so the fish neither floats up to the surface nor sinks to the bottom. Fish have an excellent sense of smell and good vision. Fish have external fertilization, sperm and eggs are released into the water where they will hopefully find each other with the exception of certain species such as the seahorse.