Lecture 8 Flashcards
Name characteristics of cartilaginous fish
1) Tesserate calcified cartilage
2) pelvic claspers in males
3) anterior fontanelle on the skull
4) placoid scales
What is tesserate calcified cartilage?
The cartilage has a unique pattern
The surface had a prismatic or honey-comb like aspect and resembles a set of closely packed tiles
It strengthens the skeleton but remains light
What are pelvic claspers?
The claspers are modified appendages of the pelvic fine in males and are used as intromittent organs for sperm transfer
Has internal skeletal support
What is the anterior fontanelle?
Is an excavation on the top surface of the braincase and results from lack of calcification
It’s function, other than making the skull lighter is unclear
What are placoid scales?
Also know as dermal denticles resemble small teeth
They have a central pulp cavity supplied with blood vessels and a layer of dentine forming the main body of the scale
These scales stop growing after a while and only increase in number with age
Name characteristics of sharks
Generally fusiform bodies Ventral subterminal mouths Large rostrum Teeth with enlarged bases Jaw suspension Paired occipital condyles Strongly calcified vertebrae
Name characteristics of skates and rays
Flattened bodies Enlarged pectoral fins fused to head Ventral gill slits and mouth No anal fin Eyes and spiracles on top of head Hyomandibular jaw suspension Highly protrusible upper jaw
Name characteristics of chimaeras or ratfish
Heterocercal to whip-like tail Mouth inferior Operculum Teeth shaped like crushing plates Presence of tenacula on their rostrum Occasional presence of poison gland Autostylic jaw suspension (upper jaw fused) No spiracle Pectoral fins dibasal, pelvis fins monobasal
Name the types of jaw suspension
Autostylic suspension
Amphystylic suspension
Hyostilic suspension
