MARINE FISH Phylum Chordata dorsal hollow nerve cord

MARINE FISH

Phylum Chordata – dorsal hollow nerve cord notochord pharyngeal slits post-anal tail 3 subphyla of Chordata…

Subphylum Urochordata Tunicates (sea squirts)

Subphylum Cephalochordata Lancelets (Amphioxus)

Subphylum Craniata (vertebrata) Fish! (and other things too)

Just a quick side note… ACORN WORMS!! Quite possibly – the evolutionary link between invertebrates and vertebrates!

Back to fishies… Class Agnatha (means “without jaws”) Jawless fish Most primitive of the fishes No jaws = no true back bone Sea lamprey No scales! Parasitic Circular mouth with rows of teeth Hagfish Predatory Knotting behavior SLIME!! hagfish slime. flv hagfish slime exp. flv

Class Chondrichthyes Cartilaginous Fishes Sharks, skates, rays Cartilage – flexible connective tissue made of cells and protein.

Cartilaginous fish continued Shark Characterisitics: • Placoid scales – tiny teeth embedded in skin (also called dermal denticles) • Visible gill slits (5 -7) • Spiracles – located behind each eye; water passes thru to gills • Wing-like pectoral fins allow lift when gliding thru water

Cartilaginous fish continued Skate and Ray Characteristics: Mostly bottom dwellers May have a sharp spine near base of tail Placoid scales Ventral gill slits Ventral mouth Spiracles

Cartilaginous fish continued Shark Structures and Behavior Lateral line – detects vibrations in water Acute sense of smell – can detect blood half a mile away Ampullae of Lorenzini – tiny pores on snout – detect electrical fields generated by muscles of fish/other prey Replaceable teeth Most stay in constant motion because if they don’t swim they will sink – also helps keep water moving over gills Eye – nictitating membrane – protects eyes while feeding Large, oily liver – increases shark’s buoyancy 5 -Liver. mov

Cartilaginous fish continued Shark Reproduction Internal fertilization Males have claspers – located near pelvic fins – transfer sperm to female’s reproductive tract There are three ways in which shark pups are born…

Cartilaginous fish continued Oviparity- lay leathery eggs. Examples are horn shark, catshark, Port Jackson Shark, and swell shark Viviparity - maintain a placental link to the developing young – like mammals. Hammerheads, requiem sharks (bull and tigers), basking sharks, and dogfish fall into this category. Dogfish have the longest known gestation period of any shark, at 18 to 24 months. Ovoviviparity - Most sharks utilize this method. The young are nourished by the yolk of their egg and by fluids secreted by glands in the walls of the oviduct. The eggs hatch within the oviduct, and the young continue to be nourished by the remnants of the yolk and the oviduct's fluids. Some species practice oophagy where the first embryos to hatch eat the remaining eggs in the oviduct. Some will even eat the remaining embryos (intrauterine cannibalism). The survival strategy for the species that are ovoviviparous is that the young are able to grow to a comparatively larger size before being born. 12 -uterus diss. mov

Class Osteichthyes Bony Fish 95% of the rest of the fish in the ocean Have skeleton made of bone Vertebrae Swim bladder Found everywhere – fresh, marine, brackish Scales – can indicate age (like rings of a tree!) Slime – mucous coating – protection against infections and reduces friction while swimming. Ocean Sunfish World’s largest bony fish (12 ft)

Bony Fish continued Breathing in Bony Fish Gills (usually only 4) Operculum (gill cover) – opens and closes to pass water over gills Gill filaments Breathing pathway Path of oxygen flow

Bony Fish continued Fish Locomotion Nekton – animals that actively swim rather than drift Provides main thrust Allow direction – up, down, forward, backward Stabilize, prevent rolling from side to side

Bony Fish continued Typical fish movements Not all fish are as streamlined. The sea horse has a rigid body and swims by undulatory movements of its dorsal fin.

Bony Fish continued Fish Locomotion continued… Body shape has a lot to do with how a fish moves

Bony Fish continued Fish Locomotion continued Fastest fish? Most open water (pelagic) fish tend to be faster Fastest fish… #1 - Swordfish #2 - Tuna

Bony Fish continued Fish Locomotion continued Temperature also affects speed Most fish are ectothermic (cold blooded). Colder temps decreases a fish’s metabolic rate which decreases muscular activity. Some predatory fish have evolved the ability to increase their body temp above that of the water.

Bony Fish continued Buoyancy in Fish Swim Bladder – internal gas-filled organ Present in bony fish Allows fish to rise, sink, or maintain a steady position in water (neutral buoyancy)

Bony Fish continued Food-Getting in Fish

Bony Fish continued Digestion and Transport in Fish One way digestive system Closed circulatory system 2 chambered heart

Bony Fish continued Sensitivity in Fish • Well developed hearing – no external ears, only an inner ear, and sound receptors located along lateral line Lateral line – series of canals – water enters, stimulates cillia on nerve cells which connects to dorsal spinal cord

Bony Fish continued Sensitivity in Fish • Excellent Sense of smell Nostrils (or nares) – nerve endings detect chem changes • Good Vision 2 eyes on each side wide field of view Most can see in color • Sense of taste Taste buds on lips, tongue, and all over mouth Some fish have barbels – whisker like projections on mouth

Bony Fish continued Reproduction in Bony Fish External fertilization – 90% of bony fish Spawning – the act of gamete release during external fert. Bony Fish Life Cycle 1. Egg stage 2. Larval stage (a few weeks, plankton-like – about 2 mm) 3. Postlarval stage (fin development active swimming) 4. Juvenile stage (looks like small adult) 5. Adulthood (sexually mature)

CLOWN FISH EXPOSE!!! Anemone clownfish are protandrous hermaphrodites, which means they can start their life as a male and then change to female. These fish are born with both male and female sex organs. The largest fish in the group is a female and the second biggest is a male. All the other clownfish are neuter, which means they have not fully developed functioning sex organs for either gender. If the female should die, the male will change sex, while the biggest neuter clownfish will develop functioning male sex organs to replace the male.

Unusual Adaptations in Fish In the struggle for survival, fish have evolved diverse adaptations in a variety of marine environments.

Camouflage in Fish Flounder Chromatophores – pigment cells that expand contract to change color Two eyes on the side of its body that faces up. Flounder are born with an eye on each side; as it grows, one eye migrates to join the other eye on the up side. How_Sea_Creatures_Use_Camouflage_to_Avoid_Predators. asf Sargassum fish Resembles the shape, color, and texture of the sargassum seaweed in which it lives.

Strange shapes and behaviors of fish Sea Horse • Live in shallow waters along Atlantic, Pacific, and Gulf Coasts • Wraps its flexible tail around grasses to remain stable. • Uses its horse-like snout like a straw to suck up plankton. • After mating, the female releases the fertilized eggs to the male’s brood pouch on his abdomen. After about 2 weeks, the babies hatch from their father’s pouch. seahorse. flv

Strange shapes and behaviors of fish Flying Fish Actually flies by vibrating its caudal fin at more than 40 beats per second to propel itself out of the water. Its pectoral fins act like wings to give lift. flyingfish. flv Anglerfish Huge mouth with spiky teeth Bioluminescence – lighted lure anglerfish. flv Ocean Sunfish Largest bony fish Swim using dorsal and anal fins Looks like “big swimming head” sunfish. flv

A Living Fossil Coelacanth • Thought to be extinct for over 60 million years • 1900 s - caught off the Comoros Islands in the Indian Ocean • 1990 s – caught off the island of Sulawesi in Indonesia • Nearly 2 meters long • Has paddle-like pectoral and pelvic fins that resemble fossils of the lobefin fish (possible ancestor of the amphibians) • Rare and protected by law coelacanth. flv

K…Bye!