Tunicates and lancelets are two groups of nonvertebrate chordates. Lancelets are small, slender fish-like animals found in sandy ocean bottoms around the world. Tunicates, also called sea squirts, are sessile filter-feeding marine invertebrates with over 3,000 species found in coastal waters. Both animals play roles in evolution studies and some tunicate compounds show promise for cancer treatment, while others can be invasive species.

1. Tunicates or “Sea squirts,”
and Lancelets
By Sandra Cash

2. General info.
∗ Nonvertebrate chordates have two groups; tunicates, and
lancelets.
∗ Lancelets, live in in all the oceans of the world in warm and
cool waters in sandy bottoms near the shore
∗ They look like slender fish without eyes. They are 0.4 to 3
inches long and whitish to creamy yellow, sometimes with
a tint of pink. V-shaped lines on the outside of lancelets'
bodies outline muscle blocks inside the body. Small bristles
surround the mouth. A fin runs along the entire back of the
animal and extends forward into a short fin over the snout
and backward into a tail fin. There is a fin on the belly
toward the rear of the animal. Paired fin-like folds in front
of the belly fin extend to the front of the lancelet.
∗ They eat plant plankton and diatoms. Plankton is
microscopic plants and animals drifting in water.

3. General info continued.
∗ Tunicates are commonly known as “sea squirts.” Tunicates are
among the most familiar marine invertebrates with approximately
3,000 species. Most species are common coastal animals occurring
in rock pools and out into deeper water to about 400 meters depth,
but can live in deeper water. They are all sessile as adults, but the
larva is free swimming. They can be either solitary or colonial. Many
species are translucent or whitish in color but some species are
much more colorful and can be red, brown, yellow, and even blue .
Sharks, skates, and other bottom-dwelling animals including
periwinkles eat them; because of this, many have poisonous flesh to
deter predators.
∗ Since tunicates are sessile, they filter feed. Filter feed is a process in
which two siphons bring in water and expel water. This water goes
to the pharynx where tiny particles are filtered out; it then leaves
through the exhalent siphon. The tiny particles, like plankton, are
trapped on a continually moving layer of mucous. The mucous is
secreted by special cells and is moved across the surface of the
pharynx . Eventually it goes into the digestive tract where both it
and the particles caught up in it are digested

4. Pictures of Lancelets & Tunicates
Lancelets Tunicates

5. Pictures of Lancelets & Tunicates
Lancelets Tunicates

6. How they respond to their
environment
Lancelets Tunicates
∗ Depending on the coarseness ∗ Filter feed, since they can not
of the sand, lancelets assume move to get food.
different feeding positions. In
coarse sand they bury their
entire body with only the head
exposed to the water. In fine
sand they lie on the bottom.

7. Usefulness to Man
Lancelets Tunicates
∗ In southern China local ∗ Tunicates are currently being
fishermen using traditional studied in science for certain
techniques fish for and eat chemical compounds useful in
lancelets. fighting cancer.
∗ The greatest importance of ∗ Also eaten in a few countries
lancelets to people, however, like Japan and France.
is in the study of evolution.

8. Unusual facts about Lancelets &
Tunicates
Lancelets Tunicates
∗ Tunicates are said to “eat its own
brain” during metamorphosis - the
∗ Lancelets have blood vessels tunicate body digests the cerebrial
but no heart. ganglion – a mass of nerves that
∗ The chest has about two have a role similar to a brain.
∗ Tunicates are currently being
hundred gill slits that do not studied in science for certain
open to the outside but empty chemical compounds useful in
into a chamber inside the body fighting cancer.
wall. The chamber empties to ∗ Tunicate blood contains a high
concentration of the metal,
the outside through a hole on vanadium.
the belly of the lancelet. ∗ Tunicates are the only animals
capable of producing cellulose
∗ Tunicates have a very short life span,
about one year and sometimes far
less.

9. Media
Tunicates
∗ Some Tunicates have recently
been discovered as invasive
species, sometimes hitching a
ride on the hulls of ships from
one ocean to another.
∗ An example of this is in
Georges Bank.

10. Relevance to organism to Minnesota
∗ There is no relevance of these animals to Minnesota,
since there is no ocean or sea.

11. Works Cited
∗ Frances, . "Tunicates & Taxonomy." . Houston
Museum of Natural Science,, 2010. Web. 27 Mar 2012.
<http://blog.hmns.org/?p=2179>.
∗ Goemans, Bob. "Sea Squirts/Tunicates." Saltcorner.
Bob Goemans, 2012. Web. 27 Mar 2012.
<http://www.saltcorner.com/AquariumLibrary/browse
sectiongroups.php?SectionID=36>.
∗ "Introduction to the Urochordata." . Regents of the
University of California, 2006. Web. 26 Mar 2012
<http://www.ucmp.berkeley.edu/chordata/urochorda
ta.html>.

12. Works Cited
∗ "Invasive Marine Species Found On Georges Bank.” NOAA.
NOAA , n.d. Web. 26 Mar 2012.
<http://www.noaanews.noaa.gov/stories2003/s2125.htm>.
∗ "Lancelets: Cephalochordata - Physical Characteristics." .
N.p., 2012 . Web. 27 Mar 2012.
<http://animals.jrank.org/pages/1662/Lancelets-
Cephalochordata-PHYSICAL-CHARACTERISTICS.html>.
∗ "Lancelets: Cephalochordata - Physical Characteristics,
Behavior And Reproduction, Lancelets And Vertebrates,
Florida Lancelet (branchiostoma Floridae): Species
Account - GEOGRAPHIC RANGE, HABITAT, DIET,
CONSERVATION STATUS." . N.p., 2012 . Web. 27 Mar 2012.
<http://animals.jrank.org/pages/1666/Lancelets-
Cephalochordata.html>.

13. Works Cited Continued
∗ “Lancelets: Cephalochordata - Behavior And
Reproduction.” N.p., 2012 . Web. 27 Mar 2012. <http://
animals.jrank.org/pages/1663/Lancelets-
Cephalochordata-BEHAVIOR-REPRODUCTION.html>.
∗ Ramel , G.. "Sea Squirts and Tunicates." Earthlife.net.
N.p., 2005. Web. 26 Mar 2012.
<http://www.earthlife.net/inverts/ascidiacea.html>.
∗ "Tunicates." Marine Education Society of Australasia.
N.p., n.d. Web. 26 Mar 2012.
<http://www.mesa.edu.au/tunicates/default.asp>.