Marine Fish Kingdom Animalia Phylum Chordata Subphylum Vertebrata All fish possess a notochord  later modified into a backbone w/ moveable vertebrae – it allows animals to bend and wiggle and serves to protect the spinal cord Ichthyology = study of fish

Typical Fish Characteristics Adapted to live in water Have gills for breathing Fins for locomotion and stabilization Internal skeleton Often covered in scales Cold-blooded (ectothermic)  colder temps. slow the metabolism

Classes of Fish Agnatha Chondrichthyes Ostiechthyes

Agnatha Jawless Most primitive Fewer in # due to inability to compete w/ jawed fish Feed by suction – have round mouths w/ rows of teeth No fins or scales Ex. hagfish and lamprey

Chondrichthyes Cartilaginous – cartilage skeleton Ventral mouth Many have replaceable razor-sharp teeth Some have small teeth but gigantic mouths Ex. rays, skates and sharks

Don’t need a skeleton to provide support Osteichthyes Bony fish Skeleton made of true bone Most successful class Terminal mouth 20,000+ species in almost every aquatic habitat Greater speed and maneuverability Specialized mouths w/ protrusible jaws Swim bladder to control buoyancy Don’t need a skeleton to provide support because the water does.

Body Forms Body shape is directly related to lifestyle. They have all types of body forms, for example: Fusiform Streamlined, torpedo shaped – “swimming machines” Designed to rapidly move through the water in pursuit of prey Efficiency is higher due to: Ability to fold fins into depressions along body Smooth eyes flush w/ head Gills covered w/ flap = operculum Slime coating Ex. salmon, bass, tuna, swordfish

Body Forms (con’t) Compressed Squished side to side Allows for easy movement among plants and narrow spaces – like coral reef Ex. flounder, perch, butterfly fish

Body Forms (con’t) Attenuated Depressed Tube like live in narrow spaces – rocks, coral reefs, etc. Usually secretes a large amount of slime Ex. eel Depressed Flattened top to bottom (dorsoventrally) Usually bottom dwellers Shape of a Hershey’s kiss Ex. sea robin, rays, skates

Depressed

Attenuated

Fins principle function is locomotion Shape is related to method of controlling position or altitude in water Shapes, sizes, and function differ from fish to fish – there are 6 Pelvic - soft dorsal Anal - spiny dorsal Caudal - pectoral

Locations of fins depends on function too: dorsal - used as rudder to prevent rolling Anal – used as a rudder Pelvic/pectoral – used in turning, braking, balancing caudal – pushes against water and used in forward mvmt.

One of the major differences b/n bony and cartilaginous fish is the shape and function of the fins: Sharks rely on fins for lift (to keep from sinking) Fin function – reason why bony fish are more maneuverable than cartilagenous fish

Three major typs of caudal fins Heterocercal – sturgeon or shark – use fins to regulate depth (no swim bladder) – also aid in swimming Pushes head downward and lifts tail as it beats side to side Pectoral fins act as airplane wings Shark fin soup – a delicacy in the orient – dump the rest of the organism back to die Ex. shark

Diphycercal No real lobes ex. lungfish

Homocercal – modern bony fish Use fins as swimming aids and for turning and stopping – or just moving forward Lobe same size Ex. perch