Marine Vertebrates Friday May 1 2015 11 27 PM C Marine Vertebrates 1 Marine fishes 2 Marine reptiles 3 Marine birds 4 Marine mammals D Marine fishes 1 Fish as vertebrates 2 Diversity of fishes 3 Specialized features of marine fishes 4 Ecological role of marine fishes E Fish as verts 1 Marine fishes show an amazing variety of adaptations to exploit nearly every ecological niche in the ocean intertidal to deepest oceans 2 Number of spp of fishes outnumbers all other chordates combined 30 000 spp of 3 From a more practical standpoint marine fish are important to humans as a source of fishes food and other products 4 All fishes have Segmental ossification of the notochord vertebrae All but hagfish have vertebrae surrounding the spinal cord Musculature that is segmented into myomeres Closed circulatory system with hemoglobin contained within red blood cells that cannot leave the blood vessels 5 Earliest vertebrates were fishes that lacked both paired fins and jaws 6 Most present day fishes have jaws and fins but some still lack those features 1 Fish can be grouped into 6 types 5 marine Diversity of fishes Agnatha jawless fish 1 Hagfish 2 Lampreys Jawed fishes gnathostomes 3 Cartilaginous fishes 4 Coelacanths 5 Ray finned fishes 6 Lungfishes 3 4 5 bony fishes Agnatha jawless fishes jawless fish lack fins and scales 1 Hagfish 70 spp all marine Lack vertebrae Feed with dental plates feed on soft bodied inverts and scavenge Marine benthic scavengers Most often occur in deep water 600 m Unique slime glands protection remove extra slime by tying themselves Lampreys 38 spp 9 marine 2 Anadromous return to FW to spawn Larvae hatch migrate downstream return to sea after as long as 7 yrs Often parasitize bony fish Mouth modified into sucker oral disk with rasping tongue and denticles to grasp prey Jawed Fishes 3 Cartilaginous fishes Sharks skates rays chimaeras Cartilaginous skeleton Jaws and paired fins Rigid fins rather than flexible Placoid scales dermal denticles Two main group Holocephalans chimaeras Elasmobranchs sharks skates rays Holocephalans chimaeras Rabbitfish ghostsharks ratfish Upper jaws attached to braincase Gills covered with operculum Flat plates in jaws to crush prey rather than teeth mollusks crustaceans echinoderms fish Some shallow usually deep water Claspers with additional clasper on head Elasmobranchs sharks 400 spp All oceans greatest spp in tropical waters Half of spp occur over continental shelf 200 m Diverse 6 in pygmy shark to 60 ft whale shark largest fish in the sea Features mostly only found in sharks Heterocercal caudal fin Reproduction Males with claspers for internal fertilization Some have placental embryonic nutrition Retain metabolic wastes urea TMAO for osmoregulation Scales are dermal denticles Carnivorous Often top apex pred Large spp are filter feeders whale basking megamouth Rows of constantly replaced teeth like conveyor belt Most with ventral mouth Used for meat fins oil leather teeth cartilage As many as 100 million sharks killed each year just in fin trade Life history characteristics make them vulnerable to overfishing boom and collapse fisheries shark bites non fatal 28 a year Fatal shark attacks average 2000 2010 is 1 a year Elasmobranchs skates and rays 600 spp Flattened body Large pectoral fins attached to head Spiracles on dorsal surface and gills on ventral surface water in through spiracles out through gills Pavement like teeth for crushing prey mollusks and other inverts Some feed on plankton mantas Includes guitarfish sawfishes Most bottom oriented Most rays give live birth Many have special defenses Skates produce mermaid purses Spines Electric organs Sawfish barbs Skates vs Rays Skates Rays Flap pectoral fins like wings Thin tails most with barbs Most give live birth Coelacanth Lobefin Fishes swim by undulating pectoral fins wave of movement Tails with fins lack barbs Most lay eggs mermaid s purse Rod shaped bones surrounded by thick muscle in pelvic and pectoral fins characteristic shared with tetrapods Skeleton of bone and cartilage Only modern representative coelocanth Thought extinct 60 mya until found in 1938 Now 2 spp Found in S Africa and Indonesia Most live at 150 250 m Give live birth Live 60 yrs mature at 20 yrs Population as small as 500 individuals 5 Ray finned fishes Also referred to as bony fishes or teleost fishes Over 26000 spp just over 50 are marine Most numerous and dominant vertebrate group in ocean Radiated into virtually every inhabitable niche in the sea Half of all vertebrate spp 90 of spp that we think of as fishes Most have Swim bladder Fins ray and variety of fins Bony skeleton Bony scales embedded in skin Operculum covering gills Two main groups Chondrostei sturgeon Cartilaginous skeleton thick scales heterocercal tail Neopterygii most bony fishes Bony skeleton bony scales homocercal tail C Specialized features of marine fishes Fish have developed a of features to deal with life in the ocean 1 Body shape 2 Coloration 3 Locomotion 4 Respiration 5 Circulation 6 Osmoregulation 7 Buoyancy 8 Special senses 9 Reproduction D Body shape Shape related to way of life Fusiform streamlined fast swimming tuna Laterally compressed butterfly fish sea grass coral reef Flattened body flounder bottom dwellers Globular body angler fish sedentary lifestyle Eel shaped long slender reduced fins E Coloration Poster coloration 1 Communication with conspecifics 2 Warning coloration spiny venomous Cryptic coloration 1 Countershading Light on bottom dark on top No silhouette viewed from above Blends in with dark water or bottom viewed from above 2 Blend with surroundings pred prey Disruptive coloration 1 Horizontal stripes disrupt body coloration 2 Common in reef fish 3 Makes it difficult for pred to see fish 4 Often with eyespot decreases ability of pred to locate head F Locomotion Variety of modes of locomotion 1 Drift crawl burrow glide and swim Trunk muscles propel fish through water 1 Arranged in W shaped bands 2 Bands contract alternately moving body back and forth Shape of the body and the swimming mode generally correlated Different swimming modes 1 Anguilliform 2 Carangiform 3 Thunniform Swimming modes Anguilliform Slender bodied fishes eels lampreys many sharks Much of the body undualates at high amplitude More efficient at lower swimming speeds Carangiform Broad tails and a narrow caudal peduncle Tail undulates at high amplitude More efficient at high speed Thunniform Lunate tails and narrow caudal peduncle Tail bats at