Lec 10 part b Flashcards
Holocephali clades
Callorhynchidae
Chimaerida
Rhinochimaeidae
Holocephali features
Teeth that form beak-like feeding aparatus
Elongate snouts for electroreception
Lack tesserae or scales
Holocephali feeding
Feed on invertebrates and small fishes near the sea floor
Holostylic jaw suspension
Holostylic jaw suspension
Palatoquadrate (P) fused to neurocranium (C)
Holocephali reproduction
Mostly solitary off mating period
Males can carry cephalic clasper for copulation
Are oviparous
Maturity at 10-12 years
Oviparous
Fertilized eggs develop outside the female body
Elasmobranchii
Sister group of Holocephali
Batomorphi 4 clades
Rajiformes (A)
Torpedoiniformes (B)
Rhinoplastiformes (C)
Myliobatiformes (D)
Batomorphi features
Wide and depressed
Eyes positioned dorsally
Gills and jawed mouth are ventral
Anal fin lost
Dorsal fin modified into tail spine with one or more venom barbs
Pectoral fins well developed and fused to head
Batomorphi swim in
Wave like motions of the pectoral
Batomorphi feeding
Most are benthic (bottom dwelling)
Durophagy
Some are piscivorous and filter feeders
Hyostylic jaw suspension allows jaw to protrude in some
Durophagy
Feeding on invertebrates with hard shells
Batomorphi hunt with
Electric organs
Electroplax tissues derived from muscles on the branchial/gill arches
Active electrogenesis
Found in some members of Torpidiniformes
Batomorphi reproduction
Some species are oviparous and some are viviparous
Viviparous
Fertilized eggs develop in female
Oral feeding starts before birth
Selachii
Sister group to Batomorphie
Shared feature of Selachii and Batomorphi
Relatively long rostrum (portion of the cranium in front of the eye)
Subterminal mouth
Hyostylic for mobile and protrusible jaws
Large nasal capsules
Squalomorphi five clades
Hexanchiformes (A)
Squaliformed (B)
Squantiformes (C)
Pristiophoriformes (D)
Echnorhiniformes (E)
Sawfish
Member of Batomorphi
Gill positioned ventrally
Lack barbels as electroceptors on the nostrum
Sawshark
Member of the Squalomorphi
Gill positioned laterally next to pectoral fin
Carrying barbels as electroreceptors on the nostrum
Squalomorphi
Carry a distinct spiracle to assist ventilation
Some species have tapetum lucidum (eye shine)
Lack anal fin
Fins with cartilaginous fin spines- Assist in stabilizing fins during movement
Hexanchiformes diagnostic features
Lack calcified vertebrae
Loss of anterior dorsal fin
Loss of fine spines
Galeomorphi 4 clades
Heterodontiformes
Orectobiformes
Lamniformes
Carcharhiniformes
Galeomorphi diagnostic features
Having small spriacle or none at all
Most species lose fin spine
Carrying anal fin
Some have tapetum lucidum
Tapetum lucidum
Formed by plate like guanine crystals behind the retina in the eye
Makes the eye shiny
Selachii feeding
Carnivorous predators
Active hunting
Ambush hunting
Found near ocean floor
Selachii hunting tactics
Suction feeding
Ramming
Biting
Suction feeding
Mouth is opened rapidly, creating negative pressure that sucks in water and prey
Ramming
Predator swims rapidly with mouth open
Biting
Predator closes jaw on prey
Selachii reproduction
Many species are oviparous some are viviparous
Selachii
Lecithotrophy
Yolk supplies all necessary nutrients
Selachii
Matrotrophy
Additional nutrients are supplied by female through placental attachment
Otodus megalodon
Likely in Galeomorphi
Usually large teeth and body size
Acanthodii
Stem-chondrichthyans in the Devonian
Small in size
Spikes on the ventral side
Lack teeth
Carry smooth scales made from bone and dentin
Helicoprion
Teeth arranged in spiral whorl all in lower jaw
New teeth rotate outward old teeth are retained
