sienna navarro 9b. meaning it comes from the greek words chondr and ichthyes = cartilaginous fish...
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Chondrichthyes & Agnatha
Sienna Navarro 9B
Chondrichthyes Meaning
• It comes from the Greek words chondr and ichthyes = cartilaginous fish cartilage fish
Chondrichthyes First Fossil
• Comes from the early Devonian age• 416 million years ago
Elasmobranches: Cladoselache
Chondrichthyes Number of Species
• 934 species: 383 species of sharks 516 species of rays• 35 species of chimaeras
Chondrichthyes Characteristics
• Endoskeleton entirely cartilaginous• Tough skin covered in dermal denticles • No Swim Bladder• Two chambered heart• Acute senses• Sharks shed and replace teeth
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”
Chondrichthyes Oviparous- “egg birth”
• Female shark deposits eggs cases in sea• Developing embryo receives nutrients from a
yolk formed prior to fertilization
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
Chondrichthyes Viviparous- “live birth”
• Embryo and attached yolk grow in uterus• Outside layer of yolk contacts mother’s uterus
• Receives nutrients
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
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
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
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
Agnatha
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
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
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
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
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
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
Agnatha Respiratory System Cutaneous Respiration
Diffusion• Dissolved oxygen diffuses into blood• Carbon dioxide diffuses out
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)
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_agnat
hans• http://biostor.org/cache/pdf/d3/c7/a7/d3c7a7457e177dd918a47080
52141bb4.pdf• http://www.waterencyclopedia.com/En-Ge/Fishes-Cartilaginous.htm
l#b• http://www.scribd.com/doc/38167359/Bio-Presentation-Chondrichth
yes• http://en.wikipedia.org/wiki/Elasmobranchii• http://www.bio.davidson.edu/courses/anphys/2000/martin/introduct
ion.html• http://www.google.com/search?um=1&hl=en&q=organic%20detrit
us&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
Bibliography• http://www.aquaticcommunity.com/mix/hagfish.php• http://www.livescience.com/13025-hagfish-eating-skin-gills-scaven
ger.html• http://en.wikipedia.org/wiki/Peritrophic_matrix• http://answers.yahoo.com/question/index?qid=20100307190830A
AE85Al• http://www.sciencedaily.com/releases/2011/02/110202132340.htm• http://www.enchantedlearning.com/subjects/sharks/anatomy/Diges
tion.shtml• http://answers.yahoo.com/question/index?qid=20080212214748A
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