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Vertebrates (subphylum vertebrata) Possess a backbone (aka vertebral column, spine) Vertebrae=Dorsal row of hollow skeletal elements (usually bone) Nerve.

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Presentation on theme: "Vertebrates (subphylum vertebrata) Possess a backbone (aka vertebral column, spine) Vertebrae=Dorsal row of hollow skeletal elements (usually bone) Nerve."— Presentation transcript:

1 Vertebrates (subphylum vertebrata) Possess a backbone (aka vertebral column, spine) Vertebrae=Dorsal row of hollow skeletal elements (usually bone) Nerve cord=spinal cord, protected by vertebrae, (part of nervous system), ends in brain Bilateral symmetry, endoskeleton

2 Fish Form & Function Goals for this lab Learn about fish: Topics –Skin/scales –Coloration –Locomotion –Fins –Muscles Discuss 3 classes of fish Dissect different fish- up to 3 different forms Write paper comparing different fish forms –Due next Monday/Tuesday –Details to follow

3 Global Habitats 58.2% 41.2% 39.9%

4 Fish importance Appeared > 500 mya Comprise half of vertebrate species Feed on all types of marine organisms some organisms previously discussed use fish as their home (bacteria to crustaceans) Some animals eat fish Most economically important marine organism Vital source of protein to millions of humans Ground up for chicken feed, fertilizer, leather, glue, vitamins obtained from them Some kept as pets

5 Fish Morphology Skin Color Bioluminescence Swimming Locomotion Fins Muscles

6 Skin Organ of the body Consists of connective tissue Muscles pull against skin tissue & skeleton Key component of the muscle-tendon-tail fin system Layers Epidermis Typically 250  m thick  cell layers Range 20  m – 3 mm Dermis

7 Fish Skin Function: Hold fish together Serves as barrier against abrasive agents Osmoregulation (what does this mean?) Permeable  respiratory function Biomechanical properties in sharks

8 Fish Skin Mucous formed in epidermis cells Protect against infection Constantly shed to remove bacteria and fungus Ex. Clingfish lack scales, protect their bodies by a thick layer of mucous Bone is also skin derivative scales, most important Derivatives:

9 Fish Scales First appear as dermal bone Found in fossil of Cambrian period (570 mya) Layered bone, solid armor-constrained movement Evolved smaller and reduced into scales 5 types of scales (examples with images to follow) Placoid Cosmoid Ganoid Cycloid Ctenoid

10 Fish Scales: Placoid Found in elasmobranchs (sharks & rays) “teeth like”, same composition As fish grows, do not increase in size, instead new scales are added

11 Fish Scales: Cosmoid In the Sarcopterygii (fish with fleshy lobe fins), primitive fish Less evolved than Elasmobranchs and Actinopterygii (fish with rayed fins) Scales found in fossil record but not in any living fish, Except in simplified version of coelocanth and lungfish

12 Fish Scales: Ganoid In primitive Actinopterygii Found in reedfish, polypterus, gar, bowfin, and sturgeons Were thick heavy scales when first appeared Rhomboid-shaped Developed into teleost scales

13 Fish Scales: Teleost scales Ctenoid scales Cycloid scales Two types: Ctenoid-higher fish Cycloid-soft-rayed, anchovies, sardine Mineralized surface layer & inner collagenous layer Scales surrounded by dermis, in dermal pockets Grow from top, bottom, and insides; overlap lower part Scales grow with fish Characterized by concentric ridges (growth increments)

14 Coloration

15 Fish display a multitude of patterns involving 2 or more colors, in many tints and shades, arranged in spots, stripes, patches, and blotches 3 Types of coloration predominant in oceans Silver – pelagic, upper zone Red – deeper zone (~ 500 m) Black or violet – deep sea Countershaded near shore and colorful in coral reefs

16 Coloration Chromatophores Colored cells from which light is reflected off Located in the skin (dermis), eyes Various colors/hues-combination of different chromatophores Functional Roles of Colors in Fishes-examples of each to follow Social Roles Advertisement Mimicry Hiding Protection from sun (especially larvae)

17 Coloration: Social roles Cleaner Fish: distinctive markings recognized by larger fish

18 Coloration: Advertisement: Bright, bold and showy males indicate: Reproductive availability, either permanently or seasonally, e.g. cichlids, wrasses, minnows, sunfish Unpalatable or venomous, e.g. lionfishes Mimicry – Disguise: Disguises: look like something in habitat, e.g. leaffish, sargasso fish Mimicry: mimic distasteful species

19 Coloration: Concealment General color resemblance – resemble background Variable color resemblance – change with background, e.g. flatfish Obliterative shading – countershading, dark above, light below (invisible fish) Disruptive coloration – disruptive contours that breakup outline; bold stripes, bars, false eye spots Coincident disruptive coloration – joining together of unrelated parts of the body to reduce recognition; e.g. sea dragon

20 Bioluminescence Most luminous fish found m depths, few shallow 3 Types of light producing methods: Self-luminous (on/off) Symbiotic bacteria nurtured in special glands Acquire from other bioluminescent organisms- diet contains light-emitting compounds Function: Concealment by counter-illumination - ventral placement matches background from above, against attack from below Dorsal photophores safeguard against predators from above Advertisement for courting, maintaining territory, to startle and confuse predators, and feeding

21 Fish Locomotion Means of Locomotion: Simplest form: Passive drifting of larval fish Some can: Burrow Walk, hop, or crawl Glide Fly Most can: Swim in a variety of ways

22 Fins Types of fins: Paired fins: pectoral and pelvic Median fins: dorsal, caudal, anal, & adipose

23 Fins Main functions: Swimming – increase surface area w/o increasing mass Stabilizers – yaw, stability-dorsal and anal fins - brake, pitch, roll, reverse -pectoral/pelvic thrust with caudal fin Modifications in fins: Defense – spines, enlarge fish Locomotion – modified for crawling, flying, gliding Hunting – lures, sensory organs Respiratory organ – lungfish, supply oxygen to eggs

24 Fins Soft rays vs. Spines Soft rays: Usually soft and not pointed Segmented Usually branched Bilateral, w/left and right halves Spines: Usually hard and pointed Unsegmented Unbranched Solid

25 Fish Muscles Muscles provide power for swimming Myomers=bands of muscle, run along sides of body, attached to backbone Constitute up to 80% of the fish itself Much hardly used except during emergencies Don’t have to contend with same effect of gravity Fish muscle arrangement not suitable on land Cow: 30% muscle/wt Tuna: 60% muscle/wt Contraction causes oscillation of body and tail Body bends as one side contracts b/c of an incompressible notochord or vertebral column Caused by bands of muscle = myomeres

26 Fish Muscles Major fibers (see handout): Red, pink, and white Pink intermediate between red and white Muscle types do not intermingle Different motor systems used for different swimming conditions Red – cruising White – short duration, burst swimming Pink – sustained swimming, used after red and before white

27 Fish Locomotion Swimming classified into 2 generic categories: Periodic (or steady or sustained)- e.g. running marathons, for covering large distance at constant speed Transient (or unsteady) – e.g. like running sprints, used for catching prey or avoiding predators

28 Undulate the body: eels, elongate fish Flex caudal portion, fast swimmers Isolate and move only fin(s) Anguilliform Carangiform Subcarangiform Ostraciform-rigid body, caudal main propulsion Thunniform-rigid body, caudal main propulsion Labriform -pectoral oscillate Diodontiform - pectoral Rajiform - pectoral Amiiform -dorsal Balistiform – anal+dorsal (Wavelike)(fanlike) Gymnotiform -anal Tetraodontiform – anal+dorsal pectoral anal dorsal

29 igger_Fish//?DVfSESSCKIE=7305db fd26 c463edc209393f8e25bdc9

30 Tuna: Ultimate Living Swimming Machine Swim continuously – feeding, courtship, rest, reproduction

31 Tuna: Ultimate Living Swimming Machine hydrodynamic adaptations Big size-high performance engine Streamlining-spindle shaped & rigid body Small structures at various parts of the body to improve swimming efficiency and reduce drag, e.g. Eyes flush with body – don’t protrude Adipose eyelid - smooth, reduce drag Depression grooves for dorsal, pelvic, & pectoral fins at high speed Keeled peduncle - cutting through water Finlets for cross-flow - delayed separation

32 Tuna: Ultimate Living Swimming Machine Must swim to survive: No gas bladder, rigid body, ram ventilation High blood volume, large heart, maintain warm core (25 o C) School to utilize vortices generated by other fish (~like race car driver who “slipstreams” and then slingshots past leading car) Adopt swim-glide for energy savings (like birds) High narrow tails – propulsion with least effort, used to design efficient propulsion systems for ships Slipstream: The area of reduced pressure or forward suction produced by and immediately behind a fast-moving object as it moves through air or water.

33 Fish-mouth types (some) Large mouth with teeth (e.g. barracuda) Long snout/small mouth (e.g. butterfly fish) Protrusible mouth (e.g. slipmouth) Large mouth (e.g. herrings) Beak-like mouth (e.g. parrotfish)

34 Fish Three Classes: Agnatha Chondrithyes Osteicthyes

35 Class Agnatha Jawless fishes Ex. Hagfish, lampreys No paired fins Gill holes, no slits or operculum Large sucking mouth with teeth Scavengers As a defense mechanism, secrete slime then tie itself in knots to escape predators Also tie in knots for pulling food off carcasses, and cleaning slime from body

36 Class Agnatha Hagfish’s mouth

37 Class Chondricthyes Sharks and rays Skeleton = cartilage, not bone Paired fins-efficient swimming Gill slits exposed, no operculum Large oil-filled liver Heterocercal tail (upper longer than lower lobe) Placoid scales-skin like sandpaper

38 Class Osteichthyes Bony fish Largest group of living vertebrates Bones for skeletons Gill covering (operculum) Swim bladder (balloon-like) Homocercal tails (even) Cycloid & Ctenoid scales

39 Dissection Worksheet Working in groups of 2 or 3 people, dissect 1 fish following the worksheet and writing the answers to the questions in your notebook as you go. Need to draw 3 external illustrations in your notebooks 1 of the fish you are dissecting, before you dissect it 2 others that have specialized mouths and caudal fins label the type of mouth and caudal fin each has Label the following structures on each illustration: gill cover, pectoral fins, pelvic fins, dorsal fin, anal fin, adipose fin (if present), lateral line give the head length, total length, and the fork length (of the dissected one ONLY, see handout) look at a scale under a microscope and draw it.

40 Dissection Worksheet continued Cut through body cavity –Find the following Heart Liver Stomach/intestines Swim bladder (if applicable) Spine Cut cross section, 2/3 down the body –Red muscle –White muscle

41 Scales- use slides Draw –Placoid –Ganoid –Cycloid –Ctenoid


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