The fishes Flashcards
What are the classes of the fishes
Myxini and petromyzondita - jawless fishes
Chondricthyes - cartilaginous fishes
Sarcopterygii - lobe-finned fishes
Actinopterygii - Ray finned fishes
Describe class Myxini (hagfishes)
No scales or jaws
Fibrous and cartilaginous skeleton
Notochord- no vertebrate
Slime glands is the defining feature- used for defense
What is the circulatory system of class myxini?
Low pressure, single circuit, 3 accessory hearts and a main one
What are some characteristics of class pteromyzondita
No scales, jaws or appendages
no stomach, spiral folds in intestine
Single circulatory system - 1 heart
What mouth do hagfish have?
Sucker mouth with rows of epidermal ‘teeth’ for attachment
Salivary glands that secrete anticoagulant
What were the 2 main important events in vertebrate evolution?
Evolution of jaws
-Better gill ventilation
-Greater variety of food sources
Evolution of paired appendages
-counteract roll in locomotion
-controls tilt and lateral motion
What is unique about class chondricythes?
Cartilaginous fishes
Cartilaginous endoskeleton - no bony skeleton
Biting mouthparts
Paired appendages
sense organs and swimming musculature
What are the 2 subclasses of chondrichthyes?
Elasmobranchii
Holocephali
What are the members of subclass Elasmobranchii?
Sharks, skates and rays
Define heterocercal tail
A tail that provides lift and thrust, upper lobe extends over the lower lobe
Define the lateral line system
Senses disturbances and vibrations in water
Made of neuromast cells in a lateral line canal
Define Ampullae of lorenzini
Sensory structures used to detect weak electrical fields, found in sharks
Explain shark digestion features
J shaped stomach
Straight intestine with a spiral valve that increases surface area
Define Oviparous
Eggs reliant on yolk, develop outside female
Define viviparous
Embryo reliant on mother via placenta, lives inside
