Phylum Chordata 1 Tunicates Amphioxus. Phylum Chordata 2 Included are 48,000 species the majority of which are vertebrates – 1,400 species are invertebrates.

Phylum Chordata1

Phylum Chordata

Tunicates

Amphioxus

Phylum Chordata3

Taxonomic Summary

Phylum Chordata– Subphylum Urochordata– Subphylum Cephalochordata– Subphylum Vertebrata

Phylum Chordata4

Subphylum Urochordata

Defining characteristics– Notochord and nerve

cord are found only in the larval stage

Most of the urochordates are filter feeders

Phylum Chordata5

Colonial Species

Phylum Chordata6

Nice Tunic

Soft exoskeleton made of cellulose with 2 external openings

Some species have spicules and toxins in the tunicate Spicules

Filter Feeding

Phylum Chordata8

Sexual Reproduction

Most colonial species retain eggs and fertilization is internal with development

The larvae are microscopic, short-lived, non-feeding, pelagic tadpoles

Phylum Chordata9

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

Phylum Chordata10

A Little Ditty

It’s a long way from amphioxus,

It’s a long way to us

It’s a long way from amphioxus

To the meanest human cuss

Goodbye to tails and gill slits,

Hello: nails and hair!

It’s a long way from amphioxus

But we came from there

Phillip H. Pope sing to the tune of “It’s a long way to Tipperary”

Phylum Chordata12

Anatomy

Phylum Chordata13

Filter Feeders

Filter feed using a special pharynx similar to tunicates

Slotted pharynx supported by skeletal bars similar to acorn worms

Phylum Chordata14

Reproduction

Separate sexes with gonads located in the atrial region– Fertilization occurs in the water– Developing young are free swimming

propelled by cilia