Chordates and Marine Fish PDF

UNIT 7: CHORDATES AND MARINE FISH Domain: Eukarya Kingdom: Animalia Phylum: Chordata Subphylum: Urochordata (tunicates) Subphylum: Cephalochordata (lancelets) Subphylum: Vertebrata (fish, reptiles, birds, mammals) Characteristics dorsal hollow nerve cord not...

UNIT 7: CHORDATES AND MARINE FISH Domain: Eukarya Kingdom: Animalia Phylum: Chordata Subphylum: Urochordata (tunicates) Subphylum: Cephalochordata (lancelets) Subphylum: Vertebrata (fish, reptiles, birds, mammals) Characteristics dorsal hollow nerve cord notocord pharyngeal gill slits endostyle or thyroid post anal tail note: all chordates possess these characteristics at some point in their life Tunicates Domain: Eukarya Kingdom: Animalia Phylum: Chordata Subphylum: Urochordata also known as sea squirts Characteristics only sessile chordate tunic (gelatinous outer covering) filter feed (incurrent and excurrent siphons) marine note: only larvae possess all three chordate characteristics, adults retain only the gills Lancelets Domain: Eukarya Kingdom: Animalia Phylum: Chordata Subphylum: Cephalochordata also known as amphioxus Characteristics retain all three chordate characteristics throughout life filter feed marine Agnathans, Bony Fish and Cartilaginous Fish Domain: Eukarya Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Supraclass: Agnatha (jawless fish) Class: Myxini (hagfish) Class: Cephalaspidomorphi (lamprey) Supraclass: Gnathostomata (jawed fish) Class: Chondrichthyes (cartilaginous fish) Class: Osteichthyes (bony fish) Characteristics dorsal row of hollow vertebrae (backbone) bilaterally symmetrical (sagittal) endoskeleton Jawless Fish Supraclass: Agnatha Characteristics eel like body (elongate) median fins lack a jaw lamprey oral or buccal funnel (sucking mouth) no scales cartilaginous skeleton lamprey parasitic dorsal nasal opening live in fresh or salt water hagfish scavengers no dorsal nasal opening live in salt water barbels hagfish Jawed Fish (Bony) Class: Osteichthyes Characteristics fresh and salt water calcium based skeleton overlapping calcium based scales operculum (gill flap) protects gills and aids in respiration swim bladder maintain buoyancy mouth is terminally located caudal fin lobes are the same size paired fins with rays lateral line sensory age can be determined by the annular rings on the scales, vertebrae or otoliths reproduction; internal fertilization (copulation) or external fertilization (spawning) hermaphroditic or non hermaphroditic oviparous (lay eggs) ovoviviparous (egg "hatches" internally and offspring are born live) Jawed Fish (Cartilaginous) Class: Chondrichthyes Characteristics fresh and salt water cartilage based skeleton non overlapping placoid scales (dermal denticles) no operculum (gill slits instead) directly open aid in respiration large oil filled liver maintain buoyancy mouth is ventrally located upper caudal fin lobe is larger than the lower lobe paired fleshy fins sensory system is efficient lateral line Ampullae of Lorenzini excellent olfaction vision is poor long distance, good short distance skates and rays have spiracles rows of triangular teeth reproduction; internal fertilization males have claspers oviparous or ovoviviparous Body Design and Locomotion Body Shape bony fish fusiform compressed (flattened vertically) depressed (flattened horizontally) elongate cartilagnious fish fusiform flattened Caudal Fins bony fish rounded truncate forked lunate cartilaginous fish heterocercal Body Fins pectoral (paired) steering dorsal vertical stability (like a sail) caudal propulsion pelvic (paired) accessory fins anal (sometimes paired) vertical stability (like a keel) Locomotion "S" motion (not "J" motion like a dolphin) rhythmic contractions of myomeres (muscle fibers/filet) Adaptations for Speedy Fish forked or lunate caudal fins fusiform body shape retractable dorsal fin pectoral fins are flush with the body reduced scales eyeballs flush with the body large heart (relative to body size) high percentage of myoglobin (high energy output) note: rays and skates have pectoral fins that are large and wide (wing like) rounded, truncate fins are good for turning and bursts, poor for maintaining speed forked and lunate tails are good for maintaining speed, poor for turning Coloration and Color Changing Uses of Color camouflage warning species recognition false message Types of Camouflage cryptic coloration blend in with the environment examples: halibut, sculpins, blennies disruptive coloration breaks up body outline examples: grouper, clownfish, zebra damsel countershading dark dorsal, light ventral examples: tuna, great white shark mimicry appear to be something else examples: stonefish, false cleaner wrasse Color Producing Cells chromatophore skin cell containing pigment irregular branching shape pigments may include yellow, red, orange or black iridophore skin cell containing guanin light reflects off of crystals in the guanin makes the fish appear to be iridescent (structural color) Feeding and Digestion Bony Fish predatory actively hunt and ambush prey barracuda, piranhas, moray eels grazing feed on algae or marine debris reef fish scavenging feed on decaying organic matter (carcasses) remoras, eels mouth --> esophagus --> stomach --> intestine --> anus * pancreas adds digestive enzymes and liver adds bile to break down fat greatwhite Cartilaginous Fish predatory actively hunt and ambush prey, using a variety of techniques/strategies great white, thresher, hammerhead, electric ray filter feeding process water over the gills to remove small planktonic material whale shark, manta ray mouth --> esophagus --> stomach --> intestine (with spiral valve) --> anus * spiral valve adds surface area to intestine for more absorption of nutrients Gas Exchange Irrigation of the Gills Bony Fish with the opercula closed, the mouth opens and water flows in the mouth closes and the opercula opens and water flows out all gills reside in a single gill chamber Cartilaginous Fish open and close mouth to move water over gills each gill resides in a separate gill chamber which opens to the outside through a separate gill slit gill arch supports gill filaments gill rakers prevent debris from entering gills gill filaments absorb oxygen lamellae increase surface area gasexchange Countercurrent Exchange oxygen level in the water must always be higher than the oxygen level in the blood for it to diffuse into the blood blood and water flow in opposite directions for gas exchange to work note: carbon dioxide works the same way rete mirabile: maintains gradient hemoglobin: protein that carries oxygen in the blood myoglobin: protein that carries oxygen in muscle tissue Osmoregulation Hypertonicity goal is to avoid dehydration bony fish swallow saltwater or absorb it through their gills the kidneys filter out excess salts bony fish excrete small amounts of highly concentrated urine in doing so the concentration of salts in the ocean and in the fish become relatively equal (isotonic) this process requires energy cartilaginous fish excrete urea Behavior and Reproduction Territories areas defended against to protect limited resources clownfish some fish defend territories only during a breeding season some fish defend permanent territories territories are most common in crowded areas where competition is high Schooling traveling in a group size varies depending on species fish keep a constant distance between each other coordination is lost feeding or are attacked protection and increased swimming efficiency Migration regular movements from one location to another occurs daily, yearly or once occurs vertically, across oceans or from ocean to freshwater salmon anadromous: fresh to salt water (salmon) catadromous: ocean to freshwater (freshwater eel) Reproduction seahorse anatomy cloaca (bony and cartilaginous fish) also known as a urogential opening claspers (cartilaginous fish) males have two they use to produce/deliver sperm courtship includes nest building, color change, drumming flashing, fin twisting, swimming in patterns mating copulation press cloacas together sperm fertilize eggs internally spawning eggs are released and fertilized externally mermaids' purses ovoviviparous (eggs hatch internally, young born live) oviparous (eggs are laid either fertilized or unfertilized)