Marine Biology Discuss: What is the Kingdom, Phylum, and Class for the following: Hagfishes: Shark: Salmon: Kingdom Animalia Phylum Chordata Class Agnatha Kingdom Animalia Phylum Chordata Class Chondrichthyes Kingdom Animalia Phylum Chordata Class Osteichthyes

Last Class We discussed three classes of fish… 1. Jawless fish, C. Agnatha, like the hagfish or lampreys These fish are composed of cartilage, lack jaws, and have an eel-like body with no paired fins or scales 2. Cartilaginous fish, C. Chondrichthyes, like sharks or rays These fish are composed of cartilage, possess jaws, and have paired fins and scales (placoid scales) 3. Bony Fish, C. Osteichthyes, like salmon and coelacanths These fish are composed of bones, bony scales, and a swim bladder.

Today! We will compare and contrast the three classes of fish by discussing: the importance of having or not having a swim bladder the importance of the ampullae of Lorenzini the importance of the lateral line system the anatomy each class of fish

Fish – Fins (p.229) Caudal fin-- provides thrust, and control the fishes direction Pectorals-- act mostly as rudders and hydroplanes to control yaw and pitch. Pelvic fins-- mostly controls pitch Dorsal/anal-- control roll

K. Animalia P. Chordata C. Agnatha (p 227) Hagfish and Lamprey Only existing representatives of the jawless fish Hagfish -Bottom-dwellers -Predator/Scavenger -Live only in the ocean -Cartilage structure -No paired fins -Slime Glands Lampreys -Filter feed as juveniles -Parasitic as adults -Adult life in ocean -Spawn in freshwater -Cartilage structure -No paired fins

K. Animalia P. Chordata C. Chondrichthyes (p229) Sharks - Skeletons composed completely of cartilage - Control buoyancy with their liver (squalene) - Detection of a drop of blood in one million parts H 2 O - Hammerhead sharks olfactory on each side of “hammer” - Lateral line system detects prey/predators - Ampullae of Lorenzini electrical impulses - Osmoregulation by retaining nitrogenous wastes

Lateral Line System (p230) The lateral line system, found in many fishes and in some aquatic amphibians, is sensitive to differences in water pressure. A swimming fish sets up a pressure wave in the water that is detectable by the lateral line systems of other fishes.

Lateral Line System

Ampullae of Lorenzini (p 231) The Ampullae of Lorenzini are small vesicles and pores that form part of an extensive subcutaneous sensory network system. These vesicles and pores are found around the head of the shark and are visible to the naked eye. The ampullae detect weak magnetic fields produced by other fishes, at least over short ranges. This enables the shark to locate prey that are buried in the sand, or orient to nearby movement.

Ampullae of Lorenzini

Nare Eye MouthPectoralPelvicAnal Lateral Line CaudalDorsal Gills

K. Animalia P. Chordata C. Chondrichthyes (p232) Rays and Skates - Flattened bodies with greatly enlarged pectoral fins - Reduced dorsal and caudal fins - Eyes and spiracles on their dorsal (top) side - Gill slits on their ventral (bottom) side - Defense of electric ray is a volt up to Defense for skates/rays is venomous dorsal fin spine/tail

K. Animalia P. Chordata C. Osteichthyes (235) Bony Fish (Salmon & Coelacanths)Coelacanths Skeleton composed of bones Buoyancy is maintained by a swim bladder, in some cases Lateral line, as in Chondrichthyes, detects prey/predators Ampullae of Lorenzini is only found on Chondrichthyes Osmoregulation is done through the gills with chloride cells Bony fish have many other adaptations and coloration patterns that we will discuss in a later class.

Swim Bladder (p 242) Swim Bladder - A swim bladder is a gas filled bag that sits in a fish's body cavity to control buoyancy. Only Ray-finned fish possess a swim bladder.

Swim Bladder

Sharks don’t have a swim bladder! What advantage would not having a swim bladder provide?

Movement of Fish The density of water makes it very difficult to move in, but fish can move very smoothly and quickly. A swimming fish is relying on its skeleton for framework, its muscles for power, and its fins for thrust and direction. The skeleton of a fish is the most complex in all vertebrates. The skull acts as a fulcrum, the relatively stable part of the fish. The vertebral column acts as levers that operate for the movement of the fish.

Movement of Fish (p 239) Thrust- force in animal's direction Lift- force opposite in right angles to the thrust Drag- force opposite the direction of movement ** All lift forces cancel out over one complete tail stroke.

Movement of Fish – Thrust and Drag Drag is minimized by the streamlined shape of the fish and a special slime fishes excrete from their skin that minimizes frictional drag and maintains laminar (smooth) flow of water past the fish. When Thrust > Drag, we have swimming!

Two Types of Swimming in Fish Cruisers: These are the fish that swim almost continuously in search for food, such as the tuna. Burst Swimmers: These fish usually stay relatively in the same place such as most reef fish.

OsmoregulationOsmoregulation (p 240) Fish need to maintain homeostasis by regulating the amount of water in their tissue by osmoregulation. Freshwater fish have more salt inside the fish so they don’t drink water because water moves into them… they have dilute urine Saltwater fish more salt outside the fish so they do drink water because they lose water to the environment… they have concentrated urine.