Chondrichthyes & Agnatha

1. Chondrichthyes & Agnatha Sienna Navarro 9B

2. Chondrichthyes • Meaning • It comes from the Greek words chondr and ichthyes = cartilaginous fish cartilage fish

3. Chondrichthyes • First Fossil • Comes from the early Devonian age • 416 million years ago • Elasmobranches: Cladoselache

4. Chondrichthyes • Number of Species • 934 species: • 383 species of sharks • 516 species of rays • 35 species of chimaeras

5. Chondrichthyes • Characteristics • Endoskeleton entirely cartilaginous • Tough skin covered in dermal denticles • No Swim Bladder • Two chambered heart • Acute senses • Sharks shed and replace teeth

6. Chondrichthyes • Life Cycle & Expectancy • Average life expectancy: 20-50 years • Longest living species: whale shark 100-150 years • 3 types of embryonic development: • Oviparous: “egg birth” • Ovoviviparous: “live egg birth” • Viviparous: “live birth”

7. Chondrichthyes • Oviparous- “egg birth” • Female shark deposits eggs cases in sea • Developing embryo receives nutrients from a yolk formed prior to fertilization

8. Chondrichthyes • Ovoviparous- “live egg birth” • Female retains membrane covered eggs • Embryo sheds membrane  develops in uterus • Some species receive nutrients from direct lining • Other species the embryo obtains nutrients by swallowing eggs / other embryos

9. Chondrichthyes • Viviparous- “live birth” • Embryo and attached yolk grow in uterus • Outside layer of yolk contacts mother’s uterus • Receives nutrients

10. Chondrichthyes • Digestive System • Swallow food whole or in large pieces • Strong acids and enzymes used to dissolve food • Creates liquid mush • Nutrients absorbed in intestine • Indigestible things are vomited

11. Chondrichthyes • Respiratory System • Species breathe through 5-7 gills • Pelagic fish must continue swimming to keep oxygenated water moving though their gills • Demersal fish pump water in through spiracles; out through gills

12. Chondrichthyes • Circulatory System • Closed circulatory system • Two chambered heart: • Atrium • Ventricle • Atrium pumps blood to ventricle • Venticle pumps blood to conus • Blood travels from conus to gills • Oxygenated blood flows through body • Blood returns to atrium

13. Chondrichthyes • Sensory System • One inner ear • Detects sound, acceleration, gravity • Lateral line • Eye sight • Sensitive to light and moving objects • Smell • Very acute • Not connected with the mouth • Barbels: responsive to chemical movement

14. Agnatha

15. Agnatha • Meaning: • It translates to “no jaws” • Number of Species • 84 species • Lampreys • Hagfish • First Fossil • Appeared during Cambrian period: • 524 million years ago • Myllokunmingia

16. Agnatha • Characteristics • Jaws are absent • No appendages • 7+ “gill” pouches • The digestive system lacks a stomach • Cartilaginous skeleton • Two chambered hearts • Slender, eel-shaped body • Notochord persists in adults • Provides support

17. Agnatha • Lamprey: Life Cycle & Expectancy • Eggs hatch - become larvae • Larvae live in river mud from 3-10+ years • Feed off of decaying organisms and fecal matter • Metamorphic Phase(3-4m) / Migrate to sea (12-20m) • Develop teeth on sucking disks • Spawning Phase (3m) / Death • Lay eggs • Die within the month spawning

18. Agnatha • Lamprey: Digestive System • Attack prey • Attach mouth to prey’s body • Cut through the skin and scales • Food = fish blood • Mouth  Pharynx  Esophagus • Esophagus directly to intestine (nutrients absorbed) • Waste released through anus • Dual immune defense system

19. Agnatha • Hagfish: Life Cycle & Expectancy • Little is knows of hagfish life span • Born fully developed • Hermaphroditic • Choose sex during mating season (can alternate) • Females lay small number of eggs for their size • Live in numbers as large as 15,000

20. Agnatha • Hagfish: Diet & Digestive System • Scavenger • Eats dead animals • Devours from inside out • Absorb nutrients through their skin and gills • Mouth is designed to tear flesh • Slow metabolism • Can survive months between feedings • Food is enclosed in permeable membrane • Waste is excreted

21. Agnatha • Respiratory System • Cutaneous Respiration • Diffusion • Dissolved oxygen diffuses into blood • Carbon dioxide diffuses out

22. Agnatha • Sensory System • 10 cranial nerves • No external ears • No eyelids • Hagfish: • Poor vision • Releases slimy mucus when in danger • Lateral line system (sense water currents/vibrations) • Lamprey: • Lateral line system • Medial nostril (“smell” perceiving chemicals in water) • Pineal organ (perceives light/dark)

23. Bibliography • http://palaeo.gly.bris.ac.uk/palaeofiles/fossilgroups/chondrichthyes/Characters/skeleton.html • http://petrifiedwoodmuseum.org/SOChondrichthyans.htm • http://www.ucmp.berkeley.edu/vertebrates/basalfish/chondrofr.html • http://www.newworldencyclopedia.org/entry/Agnatha#Fossil_agnathans • http://biostor.org/cache/pdf/d3/c7/a7/d3c7a7457e177dd918a4708052141bb4.pdf • http://www.waterencyclopedia.com/En-Ge/Fishes-Cartilaginous.html#b • http://www.scribd.com/doc/38167359/Bio-Presentation-Chondrichthyes • http://en.wikipedia.org/wiki/Elasmobranchii • http://www.bio.davidson.edu/courses/anphys/2000/martin/introduction.html • http://www.google.com/search?um=1&hl=en&q=organic%20detritus&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&biw=1088&bih=570&ie=UTF-8&sa=N&tab=iw&ei=2xFET4G7BcGg0QW_t7mPDw • http://en.wikipedia.org/wiki/Hagfish • http://staff.tuhsd.k12.az.us/gfoster/standard/zoagnath.htm

24. Bibliography • http://www.aquaticcommunity.com/mix/hagfish.php • http://www.livescience.com/13025-hagfish-eating-skin-gills-scavenger.html • http://en.wikipedia.org/wiki/Peritrophic_matrix • http://answers.yahoo.com/question/index?qid=20100307190830AAE85Al • http://www.sciencedaily.com/releases/2011/02/110202132340.htm • http://www.enchantedlearning.com/subjects/sharks/anatomy/Digestion.shtml • http://answers.yahoo.com/question/index?qid=20080212214748AAlEU7r