Chondrichthyes - Cartilaginous Fishes Flashcards
What are the key features of batoids (skates and rays)?
~700 species (more diverse than sharks).
Dorso-ventrally flattened.
Dorsal eyes/spiracles, ventral gills.
Protrusible mouth with crushing teeth.
Benthic, some freshwater.
how do skates and rays differ
Skates: Thick tail, 2 dorsal fins, oviparous.
Rays: Whip-like tail, venomous barbs, viviparous.
What distinguishes galeoid and squaloid sharks?
Galeoid sharks: Shallow, warm water, pelagic, streamlined, muscular. High metabolism (e.g., great white shark, hammerhead).
Squaloid sharks:
Deep cold water, eel-like, slow swimming, no anal fin.
Low metabolism, low productivity.
What causes sibling conflict in sand tiger sharks?
Embryos cannibalize siblings.
Up to 12 embryos, but only 1-2 survive.
What are reproductive traits of Chondrichthyes?
Internal fertilization with pelvic claspers.
No parental care after birth.
what are the different Maternal care variable
Oviparous (egg hatch).
Viviparous (live birth with placenta).
Ovoviviparous (egg nourished internally; live birth).
Describe placoid scales and shark teeth.
Dermal origin.
Modified into replaceable rows of teeth.
How are shark jaws adapted for feeding?
Hyostylic jaw suspension:
Lower and upper jaws attached to chondrocranium via hyoid arch. Jaws protrude forward.
are jaws and teeth the same things?
false they differ from each other since teeth just sit on top of the jaw
What sensory adaptations aid predation in sharks?
Keen sense of smell (“swimming noses”).
Neuromasts (vibration/sound detection).
Lateral line system (mechanical).
Ampullae of Lorenzini (detect bioelectric fields).
Good low-light vision.
explain what Neuromasts are
are cells/neurons that are sensitive to vibrations/sounds
(lateral line system) (mechanical)
What are key traits of subclass Elasmobranchii?
sharks, skates, rays, 5-7 pairs of gill slits, spiracles behind eyes.
Streamlined fusiform body, torpedo-shaped.
Asymmetrical heterocercal tail for thrust/lift.
Paired pectoral and pelvic fins
What are key traits of subclass Holocephali?
(ratfish, rabbitfish, chimaeras).
Found in benthic, deep water. Mechanoreceptors/electroreceptors on rostrum.
Fused crushing tooth plates.
Oviparous (shallow water eggs).
What does it mean to have “bone”?
Bone contains blood flow and cells.
Calcified cartilage is not true bone.
Phosphatized mineral tissues are found in teeth, scales, and spines.
What are Chondrichthyes key features?
Cartilaginous skeleton, Well-developed sense organs
Powerful jaws (predator lifestyle)
Placoid scales
Strong swimming musculature,Includes sharks, skates, rays, and chimaeras
