Non-Vertebrates
Period 5
Umer Khan
James Trimble
General Characteristics



Small filter-feeders
Lack big brains and
enhanced sensory
structures
Has a set of characters
that unifies the phylum:
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

a notochord
A perforated pharynx (gill
silts)
A dorsal nerve cord
A post anal-tail
Classes within the phylum

There are two subphyla:
1. Urochordata
represented by Tunicates
http://www.tunicates.com/tunicates.jpg
2.Cephalocordata
represented by Lancelets
http://www.nationmaster.com/wikimir/images/u
pload.wikimedia.org/wikipedia/commons/thumb/
a/a0/Branchiostoma_lanceolatum.png/250pxBranchiostoma_lanceolatum.png
Body Plan: Tunicates
http://kentsimmons.uwinnipeg.ca/16cm05/16labman05/lb7pg1_files/tunicates.jpg
Body Plan: Lancelets
http://kentsimmons.uwinnipeg.ca/16cm05/16labman05/lb7pg1_files/amphioxsis.jpg
Feeding: Tunicates
Suspension feeders
 Two openings in their body cavity:

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In-current – intake food and water
Ex-current – expels waste and water
Feed by filtering sea water through
pharyngeal slits
 Primary food source is plankton
 Pharynx is covered by ciliated cells which
allow consumed plankton to pass through
the esophagus.

Feeding: Lancelets
Suspension feeders
 Water passes from the mouth into the
large pharynx
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The ventral surface of pharynx contains
the endostyle

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Lined by gill-slits
Endosytle produces a film of mucus
Ciliary action pushes the mucus in a film
over the surface to the gill slits, trapping
suspended food particles as it does so.
Respiration
Lancelets
 Have no respiratory system
 Breathe solely through their skin


Skin consists of a simple epithelium
Little respiration occurs in the gill slits

Silts are primarily devoted to feeding
Tunicates
 Gas exchange occurs across the gill and
also across the lining of the atrium
Circulation
Lancelets
 The circulatory system does resemble that
of primitive fish in its general layout, but
is much simpler, and does not include a
heart.
 There are no blood cells
 No hemoglobin
Tunicates
 Controlled by blood vessels that circulate
through the exoskeleton
Excretion
Lancelets
 The excretory system consists of
segmented “kidneys” containing
protonephridia instead of nephrons
 There are numerous, segmented gonads
Tunicates
 Wastes are excreted through the intestine

The intestine ends as an anus in the atrium
below the atrial aperture
Response
Lancelets & Tunicates
 Have a dorsal nerve cord not protected by
bone

Protected by notochord
Do not posses a true brain
 No complex sense organs comparable to
those of vertebrates

Movement
Lancelets
 Have a translucent, fish-like body, but without
any paired fins or other limbs
 Poorly developed tail fin

Are not efficient swimmers
Do posses some cartilage but no true skeleton for
movement
Tunicates
 Movement is controlled by the cerebral ganglion

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Movement is equivalent to the human brain
Reproduction
Lancelets
 Have separate sexes
 Equal numbers of males and females
 Egg and sperm are released into the water

The fertilized eggs develop into larvae
Tunicates
 Reproduce asexually and sexually
 Reproduce by budding
 Have one testes and the ovary organ inside the
body
 Fertilization takes place outside and eggs are
produced inside
WORKS CITED

Bassham, Susie. "Chordates." N.p., 2010. Web. 20 Apr 2010.
<http://www.neuro.uoregon.edu/postle/people/Bassham.html>.

Holland, L.Z. "Early Development in the Lancelets." The Biological
Bulletin. Marine Biological Laboratory, 1992. Web. 20 Apr 2010.
<http://www.biolbull.org/cgi/content/abstract/182/1/77>.

"Lancelets: Cephalochordata." Animals Jrank. Net Industries,
2010. Web. 20 Apr 2010.
<http://animals.jrank.org/pages/1663/LanceletsCephalochordata-BEHAVIOR-REPRODUCTION.html>.