ZOO 102 - LAB1

• phylogenetic tree or dendrogram - used to represent evolutionary relationship

  among organisms
• 1 or + - denotes the presence of that character
• 0 or - - denotes the absence of that character
• law of parsimony - the best reconstruction is the one that requires the fewest evolutionary changes
• amphioxus - Branchiostoma lanceolota
• amphioxus/lancelet - a small, primitive, marine chordate belonging to the subphylum Cephalochordata. These organisms are not vertebrates like fish, reptiles, or mammals, but they share some characteristics with vertebrates and are considered a valuable evolutionary link in the study of chordate evolution.
• amphioxus circulatory system - lacks a heart and is composed of vessels and tissue channel that forms a continuous circuit. Blood is colorless.
• amphioxus nervous system - lacks brain (vertebrates are the only chordates that have the brain as part of the central nervous system)
• amphioxus skeletal elements - verebral column, cranium
• amphioxus similarities with vertebrates:

  Notochord

  Pharyngeal slit

  Dorsal Nerve Cord

  Endostyle

  Postanal Tail

  Myomeres/segmented muscles

  Gut Structure
• 1:2:2:1 - spermatogenesis ratio
• blastomeres - cells in the blastula
• blastula - growing zygote during cleavage
• higher concentration of yolk - the zygote won't grow
• fertilization - The process by which the two gametes (male and female) fuse to become a zygote. May be internal or external
• cleavage - process of repeated mitotic cell division of the zygote
• spiral cleavage - formation of tissues and organs, cell differentiation, and axis formation
• radial cleavage - the formation of the embryo from the inner cell mass.
• gastrulation - Establishment of germ layers and body axis
• neurulation - Formation of ectodermal or neural tube

  Begins when mesoderm signals the ectodermal cells above it to elongate.

  The notochord induces its overlying ectoderm to become neuroectoderm and develop into neural plate
• frog skin:

  blood vessel

  poison gland

  chromatophores

  mucus glands
• human scalp:

  stratum corneum

  stratum germinativum

  sebaceous gland

  sweat gland

  dermis

  hair follicle

  hypodermis
• pterylae - precise tracts in bird skin where feathers are confined
• Apteria – areas devoid of feather
• label

  A) hatschek's pit

  B) oral hood

  C) buccal cirri

  D) wheel organ

  E) pharyngeal slits

  F) velum

  G) notochord

  H) endostyle

  I) dorsal tubular nerve chord

  J) iliocolon ring

  K) intestine

  L) midgut caecum

  M) hindgut

  N) caudal end / post-anal tail

  O) anus

  
• label

  A) dorsal ridge / fin

  B) dorsal tubular nerve chord

  C) notochord

  D) pharyngeal bars

  E) pharyngeal slits

  F) pharynx

  G) caecum

  H) endostyle

  I) metapleural folds

  J) testis

  K) metapleural folds

  L) ovary

  M) myosepta

  N) myomeres

  
• label

  A) vegetal pole

  B) animal pole

  
• label

  A) micromeres

  B) blastocoel

  C) macromeres

  D) ectoderm

  E) dorsal blastopore / lip