Phylum Chordata (fish) lab notes

BIOL 3270 - Zoology


PHYLUM CHORDATA

Subphylum VERTEBRATA (“Fish”)

FEATURES
 All have a cranium with complex sensory organs
 Paraphyletic lineage
 Mineralized tissues (not necessarily bone)
 Increased body size and activity (all are greater than 10cm in length)

Class Petromyzontida (lampreys)

 They do not have vertebrae but instead possess cartilaginous skeletal elements called
arcualia which are homologous with neural arch of vertebrae.
 the notochord is still the main means of support down the long axis of the body.
 They lack jaws
 Possess a piston-like tongue for rasping at their food.
 Single nasal opening
 Well-developed eyes
 Pituitary gland
 2 semicircular canals for water orientation.
 Half are parasitic as adults.
 The ammocoetes larva burrows into the silt on the bottom of the ocean and can live there
for 3-7 years.

Ammocetes larva
IDENTIFY
 Notochord
 Nerve cord
 Pharyngeal slits
 Post-anal tail
 Endostyle (end of tail)
 Nostril
 Eyespot
 Velum
 Heart
 Liver


External anatomy

, BIOL 3270 - Zoology


IDENTIFY
 Dorsal and caudal fins (tail fin for propulsion)
 Gill opening
 Nasohypophyseal opening
 Eye
 “teeth” (not true teeth)
 Tongue (used to siphon food)
 Oral hood (mouth)

Internal anatomy
IDENTIFY
 Mouth
 Tongue muscle
 Nasohypophyseal duct (AKA pituitary gland – duct from nostril to brain)
 Olfactory sac
 Brain
 Pineal eye (gland) (part of the brain – night/day)
 Spinal cord
 Notochord
 Heart
 Pharynx
 Intestine
 Gonads
 Myomeres of muscle




Class Chondrichthyes (cartilaginous fish)

Subclass Elasmobranchii (sharks, skates, and rays)