BIOLOGY 456- ZOOLOGY LABORATORY 7: FISH AND
AMPHIBIANS LATEST REVISED STUDY GUIDE 2026
Part 1: Zoology Basics – Modes of Reproduction
- 3 modes of reproductions
o Oviparity: ancestral condition whereby eggs are laid with little to no other
embryonic development within the mother, split into
▪
Ovuliparity: external fertilization
▪
“true ovilparity” : internal fertilization
o Viviparity: development of embryo occurs inside the body of the parent leading
to live birth
o Ovoviviparity: embryos that develop inside hehs remain the parents body until
they hatch
▪
There is no placental connection between parent and embryo
▪
Embryo nourished by egg yolk
Part 2: Superclass Agnatha
- General Characteristics
o Jawless fish Represent most basal group of craniate
o Two classes of jawless fish were thought to be polyphyletic
o Now, established as monophyletic
- Taxonomic classification
o Class Myxini
▪
Hagfish (scavengers)
▪
No eyes
▪
Find prey using tactile and olfactory clues
o Class Petromyzontes
▪
Lampreys
▪
Mostly parasitic jawless fish
▪
Ammocoete larvae similar to Cephalochordates
- Diversity
o Class Myxini
▪
Hagfish body is eel-like, long slender
▪
Atriopore: single gill pore
▪
No paired appendages
▪
Fin is a single diphycercal caudal fin
▪
Scales absent
▪
Row of pores run down body
▪
Pores connect to slime sacs
▪
Slime sacs produce slime as a defense mechanism
o Class Petromyzontes (Cephalopidomorphi)
▪
Include lampreys: anadromous or strictly freshwater fish
▪
Many parasitic
•
Suck blood of living fish
▪
Non-parasitic form only feed as larvae and are short living adults
