8SUPER CLSS AGNATHA Superclass Agnatha – 70 species General Characteristics1. Body – long, cylindrical (eel like)2. No scales, jaws, or paired fins3. Two chambered heartpairs of gills5. poikilothermic – having a body temperature that varies with the temperature of its surroundings
9HagfishMarine, feed on dead or dying organisms (not parasitic)When caught, secretes enormous quantities of slimy mucusEnters body of an animal through gills, mouth, or anus and eats the contents of the body leaving a sack of bones and skinLamprey40 species, fresh and marine water, parasitic
10Reproduction (Hagfish and Lamprey) Both ovaries and testes present, but only one is functionalMales build nests in spring and fertilization is external (2-65,000 eggs)Adults die after spawningEggs hatch into larvae and burrow into sand or mudEmerge at night to feed, blind and toothlessLarval form for 3-7 yearsMetamorphosis into adult takes about 4-11 months
11Lamprey is food for humans Economic importanceFish baitLamprey is food for humansFYI…Portuguese and Spanish diners prize sea lamprey as a gourmet treat for which they're willing to pay up to $25 a pound. European fishers harvested local lamprey so much that populations on that side of the Atlantic are crashing, allowing demand for this prehistoric boneless fish to exceed supplies.So what does lamprey taste like? "I would have to say it tastes like lamprey," says Chef Bob Bennett, "because it does not have a flavor that you can associate with anything else."When pushed further, he volunteered that "its taste is not offensive. A lot of delicacies that I've been introduced to over the course of my career are a lot less palatable - such as the sea urchin."Hagfish will damage fish caught in net or line
12Some differences between sharks and fish Sharks FishMade of cartilage Made of bones and cartilageCan only swim forward Can swim forwards and backwardsUses oil for buoyancy Uses gas-filled swim bladder for buoyancyEggs fertilized in females body Eggs fertilized in waterSkin is rough like sandpaper Slippery scales on skin
14Dorsal fins – keep upright Caudal fins – forward thrust Heterocercal - dorsal lobe is larger than ventralHomocercal – dorsal and ventral lobes are the same sizePectoral and pelvic fins – steering
15Clasper – (male) on pelvic fin used in mating They use one at a timeAfter communicating its intentions to a receptive female shark through ritualized swimming and gentle 'love nips' along her back or flanks, the male grasps one of her pectoral fins and docks next to her.If the male happened to dock along the left side of the female, he flexes his right clasper across the mid-line of his body and inserts it into her vent (genital opening).MALEFEMALE
16Eyes – lower lids to cover eye when feeding Mouth – ventralEyes – lower lids to cover eye when feedingGill slits – 5-7 pairs; used for water to exitSpiracle – modified gill slit on top of headPurpose: provide oxygenated blood directly to the eye and brain through a separate blood vessel.Absent or reduced in many sharks, especially the fast swimming sharks and is usually larger and present in bottom dwelling sharks. In the rays, the spiracle is much larger and more developed and is used to actively pump water over the gills to allow the ray to breathe while buried in the sand.
17Vent- opening to cloaca; analogous to anus Latin: “sewer” Cloaca - common chamber that intestinal, urinary, and genital tracts open.FYI: It is present in amphibians, reptiles, birds, sharks, and monotremes. A cloaca is not present in placental mammals or in most bony fishes.
18Lateral line – sensory system detecting and locating objects Made of cells called Nematocysts (sensitive gel filled cells that transmit signals to nerves)Sensitive to vibrations and currents
19Ampullae of Lorenzini – gel-filled pores on face sense bioelectric fieldsA biolelectric field surrounds all animals. Sharks can even detect animals under the sand!It looks like a 5 o’clock shadow
20Placoid scales – backward pointing spine covered by enamel
21Skeleton – cartilage Axial – skull and vertebral column Appendicular – pectoral girdle (front fins) and pelvic girdle (pelvic fins)
22Teeth -replaced throughout life of fish Tongue -immobile Digestive systemMouthTeeth -replaced throughout life of fishTongue -immobileEsophagus -shortStomach -J shapedPylorus -valveIntestine -spiral valveCloaca -common chamberVent -anusLiver -very large, oily, purifies bloodGall bladder -near top of liver, stores bile collected from liver and passes bile to intestines through bile ductPancreas – between stomach and intestine, secretes digestive enzymes that are released into intestineRectal gland – located near most posterior part of abdominal cavity; regulates excess salt received from food and water
23Coelom Peritoneum – lining the abdominal cavity Made of layers Outer layer - parietal peritoneum, is attached to the abdominal wallInner layer - visceral peritoneum, is wrapped around the internal organs located in inside the abdominal cavityMesenteries – membranes that attach organs to the abdominal wall, hold intestine in place
24Heart is covered by a visceral pericardium The heart is S-shaped Circulatory SystemSharks have a two-chambered heart, with an atrium (aka auricle) and a ventricle.Heart is covered by a visceral pericardiumThe heart is S-shapedventral aorta transports blood to the gillsdorsal aorta takes blood back to the heartVesselsCarotids – carry blood to and from headSubclavians – carry blood to and from pectoral finsMeaning “subclavical”, under the clavicalRenal – carry blood to and from kidneysHave you ever heard of renal failure in cats? Renal is from the Latin word renes which means kidneysIliacs – carry blood to and from pelvic finsFrom the Latin word ilia describing the bones that make up the pelvis
26Sketch a shark: LABEL the Anterior dorsal finPosterior dorsal finHomocercal caudal finPelvic finPectoral fin
272. What is the function of the spiracle? 3. What is the function of the ampullae of lorenzini?4. Why do sharks have a large liver?5. What is the function of the clasper?6. What is the function of the cloaca?
289. What kind of fish eats out the insides of a dead organism? 10. What class do sharks belong to?11. What class do bony fish belong to?12. What shape is the sharks stomach?13. How many chambers are in a sharks heart?
29Sketch a shark: LABEL the Anterior dorsal finPosterior dorsal finHomocercal caudal finPelvic finPectoral fin
302. What is the function of the spiracle? Provide oxygenated blood directly to eyes and brain3. What is the function of the ampullae of lorenzini?Sense bioelectric field4. Why do sharks have a large liver?Produces oil5. What is the function of the clasper?Reproduction (male part)6. What is the function of the cloaca?Common chamber for intestines, urinary, and genitial
319. What kind of fish eats out the insides of a dead organism? hagfish10. What class do sharks belong to?Chondrichthyes11. What class do bony fish belong to?Osteoichthyes12. What shape is the sharks stomach?J13. How many chambers are in a sharks heart?two