http://funscubadiver.com/gallery/belize-scuba-photo/belize-painted-tunicate.jpg

Lancelets and Tunicates Tadpole-like larvae A notochord, semi-flexible rod running

down the length of the animal A dorsal nerve cord Pharyngeal slit, an opening between the

throat and the outside Post-anal tail, waste is excreted at the

posterior end Aquatic animals

http://en.wikipedia.org/wiki/File:Branchiostoma_lanceolatum.jpg

http://en.wikipedia.org/wiki/File:BU_Bio.jpg

http://jellieszone.com/images/oikopleura.jpg

http://www.meer.org/M20.htm

http://www.meer.org/M20.htm

A characteristic of the invertebrate chordates is bilateral symmetry (symmetry along one axis)

Very long, tubular body structure

Little specialization Segmentation of the

embryo usually occurs early in development

Has a coelomate (fluid-filled body cavity)

Is a deuterostome (first opening of the embryo becomes anus while the opposite side becomes the mouth)

http://www.bumblebee.org/invertebrates/images/AmphioxusLanceolatus.jpg

http://biodidac.bio.uottawa.ca/ftp/BIODIDAC/ZOO/CHORDATA/DIAGBW/UROC005B.GIF

                 

Are filter feeders of the water; Lancelets use their pharyngeal-gill slits to take in water

Lancelets burrow in soft ground with their mouth facing upward to filter-feed

Urochordates take in water to their body cavity to siphon food (usually plankton)

Plankton gets entangled on the mucus on the endostyle (cavity wall)

http://comenius.susqu.edu/bi/202/Animals/DEUTEROSTOMES/cephalochordata/uwinnipeg-Lancelet.jpg

Lancelets (cephalochordata) do not use the gills for respiration but resperate through their skin

Urochordata use an internal gill to extract oxygen from the water they take in

http://www.bethel.edu/~johgre/bio114d/LowerVerts.html

Lancelets: closed circulatory

system (has vein and vessels)

pumped by ventral aorta to branched vessels

Lacks a heart Colorless blood

Urochordatas:

•Open circulatory system

•Has a ventral heart

•Contains high levels of metal in blood such as lithium and vandium

Lancelets have a one way stream of wastes that exit the anus

Urochordates take in water through one entrance, extract the food and oxygen before pumping out another entrance

http://ian.umces.edu/imagelibrary/displayimage-4350.html

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/chordate.gif

Lancelets: Has a dorsal

nerve running down its body

Slightly larger end at the front which is its brain

Cephalization occurs

Urochordatas:

•Has a nervous system in the larvae stage

•Digests its own brain in the mature stage

•Nervous system soon disintegrates

Lancelets: Are feeble

swimmers Use contraction

of muscles to move the tail from side to side

Urochordata:•Are motile during their larvae stage; they have a tail to swim with•Once they become mature, they attach to a substrate and become non-motile

Lancelets: Is gonochoristic

(there’s a male and female individual)

Releases the appropriate sex cell into the water

Fertilization is external

Develops into a larvae stage

Urochorata:•Contain both male and female parts (hermaphrodites)•Do not fertilize themselves but send sperm out to fertilize other indivduals•Keeps the eggs inside themselves

“Chordata.”Bumblebee. 2010. Web. 4/16/2010.

http://www.bumblebee.org/invertebrates/CHORDAT A.htm

“Subphylum Urochordata (tunicates)” Meer. Web. 4/16/2010. http://www.meer.org/M20.htm

“Introduction to the Urochordata.” UCMP. 4/16/2010. http://www.ucmp.berkeley.edu/chordata/urochordata. html

“Introduction to the Cephalchordata.” UCMP. 4/16/2010. http://www.ucmp.berkeley.edu/chordata/cephalo.html