Unit 2 Flashcards
(19 cards)
Cyclostomata characteristics
- Single median nostril
- Unarticulated gill arch (A/B)
- Gill arch lateral to gills (C/D)
- Velum ventilates gills
- Tongue w/keratinous teeth
- Periocular trunk muscles
- Immune system ≠ Gnathos
Hagfishes & Lampreys
sister groups
notochord into adult
Hagfishes (75 spp.) Structural characteristics
- Barbels
- Keratinized teeth
- Median Nostrils
- Olfaction & Ventilation
- Variable gill openings
- Single median fin
- Notochord into adulthood
hagfish Plesio- or Apomorphic?
- Rudimentary eyes
- No electroreception
- No lateral line
- Single semicircular canal
- Pronephric kidney
- Accessory hearts
Myxiniformes
- Traits
- Elongate; Scaleless
- 0.5 m TL
- Copious slime!
- Ecology
- All marine; Deep/Cold
- Scavengers
- Physiology
- Osmoconformers
- Olfaction dominated
- Many hermaphroditic
Lampreys (40 spp.) Synapomorphies
- 7 pairs of gill pouches
- Nostril & Nasohypophyseal duct
- Ends blindly;
- no connection to OC
- Large, lateral, well dev’d eyes
- Pineal eye (homo to pineal gland)
- Piston cartilage & tongu
Ecology of lampreys
- Filter feeders
- Larvae (ammocoete)
- Endostyle
- Parasitic (Great Lakes*)
- Adults; fishes
- Keratinized tongue
Physiology of lamprey
- Filter-feeding larva
- Flow-through ventilation
- In mouth gills
- Parasitic adults
- Tidal ventilation
- In and out of gill pouches
- Velum prevents b-up
- Osmoregulators
Reproduction of lamprey
- Anadromous
- Ocean River
- Potamodromous
- Lake River
*semelparous
Gnathostomes
jaw mouth
* Early Silurian
* Joints b/w gill arches
Gnathostomes traits
Jaws w/true teeth
* Dentine + enamel
- Fins
- Two dorsal fins
- Two sets of pair fins
- W-shaped myomeres
- (4) Clusters of Hox genes
- More dev. genetic control
- Novel feeding behaviors
- Grasp prey
- True predators
- More powerful swimming
- Sophisticated maneuvering
- Hydrodynamic shape
larger body size
origin of jaws
- Single vs. Double Nostrils
- Single lies over forebrain
- Not enough space for jaws
- Ventilation hypothesis
- More space More volume
- More volume Suction feeding
origin of appendages
- 2 (Osteo) to 3 (Gnatho) pairs
- Tribasic (three elements)
- Cyclos (no horizontal sep)
- Differing developmental origins
Placoid Scales
- Dermal denticles
- Pulp, Dentine, & Enamel
- Lost dermal bone
- Retained scales
- “Outside In”
- Teeth from Placoids
- “Inside Out”
- Teeth from Pharynx
- Placoids from Teeth
Calcium hydroxyapatite
Calcified NOT ossified
Internal Calc; Vertebrae
Surface Calc; Jaws
Teeth & tooth plates
Constantly replenished
Sharp/Pointed; Snares
Serrated/Triangular; Large bites
Inward Cusp/Serrated; Saw
Molariform/Flat; Grinding
Tooth plates; Grinding
Chimaeriformes
- 56 extant spp.
- Deep water dwelling
- Whip-like tail
- Undulatory swimming
- Large eyes/broad tooth plates
- Oviparous
Specialized structures in Chimaeriformes
- Spine + venom gland
- Cephalic clasper (head)
- [Ampullae] on “plow”
Actinopterygian Traits
- Ossified skeleton
- Gas-containing lung
- Lung gas bladder
- Dermal bones
- Lepidotrichia
- Bony fin rays
- Early Ancestral enamel on scales
- Cosmoid scales (bone + cosmine + enamel)
- Ganoid scales (bone + ganoine + enamel)
cycloid and ctenoid
