Tunicates

1
Phylum Chordata

• Tunicates
• Amphioxus

2
Phylum Chordata

• Included are 48,000 species the majority of which
  are vertebrates
• 1,400 species are invertebrates
• All chordates share 4 characteristics at one
  point throughout the lifecycle
• Includes the tunicates, the lancelets
  (Amphioxus), and vertebrates

3
Taxonomic Summary

• Phylum Chordata
• Subphylum Urochordata
• Subphylum Cephalochordata
• Subphylum Vertebrata

4
Subphylum Urochordata

• Defining characteristics
• Notochord and nerve cord are found only in the
  larval stage
• Most of the urochordates are filter feeders

5
Colonial Species
6
Nice Tunic

• Soft exoskeleton made of cellulose with 2
  external openings
• Some species have spicules and toxins in the
  tunicate

Spicules
7
Filter Feeding
8
Sexual Reproduction

• Most colonial species retain eggs and
  fertilization is internal with development
• The larvae are microscopic, short-lived,
  non-feeding, pelagic tadpoles

9
Subphylum Cephalochordata

• Defining characteristics
• The notochord extends beyond the nerve cord to
  the anterior end of the animal
• The notochord is contractile, formed as a
  longitudinal series of flattened discs

10
A Little Ditty

• Its a long way from amphioxus,
• Its a long way to us
• Its a long way from amphioxus
• To the meanest human cuss
• Goodbye to tails and gill slits,
• Hello nails and hair!
• Its a long way from amphioxus
• But we came from there
• Phillip H. Pope sing to the tune of Its a long
  way to Tipperary

11
Anatomy

• Diagnostic chordate features are found in both
  the larvae and adult
• Resemble small fish with a poorly developed head
• Have cirri around a large mouth
• V-shaped body muscles (myomeres) extends the
  length of the body and are used for swimming and
  burrowing

12
Anatomy
13
Filter Feeders

• Filter feed using a special pharynx similar to
  tunicates
• Slotted pharynx supported by skeletal bars
  similar to acorn worms

14
Reproduction

• Separate sexes with gonads located in the atrial
  region
• Fertilization occurs in the water
• Developing young are free swimming propelled by
  cilia