NEMATOMORPHA
Sarah Berube
Naomi Demers-Agterberg
Mike Downing
Miranda Downing
GORDIOIDEA AND THE GORDIAN KNOT
• In Greek mythology, King Gordius, fastened his wagon to his
horse's yoke with a knot that was impossible to untie.
• An oracle announced that whoever released the knot would be
the next ruler of Asia.
• Alexander the Great cut the Gordian knot with his sword, and
went on to conquer Asia.
PLACE IN HISTORY
• Nematomorpha (from the Greek nema, "thread,"
and morphe, "shape")
• The first known fossil record of Nematomorpha dates
from the Eocene (40 - 70 million years ago)
CLASSIFICATION
• Domain: Eukarya
• Kingdom: Animalia
• Phylum: Nematomorpha
• Classes: Gordoida and
Nectonematoidea
• Species: 240
GORDIOIDEA AND NECTONEMATOIDEA
• Gordioidea live in freshwater(>200 species)
• Nectonematoidea live in saltwater, and do not
use terrestrial hosts (5 known species)
• Both genera prefer shallow water, and
nectonematoidea stay in coastal areas.
• While Gordioidea is scattered across the
globe, nectonematoidea has only been found
in restricted areas of the United States, Europe
and the Bay of Fundy.
MORPHOLOGICAL FEATURES
• No excretory pores or lateral
chords.
• Nervous system made up of
dorsal ganglion and ventral
chord.
• Gonads open into posterior
cloaca with intestine.
Larval Hairworm
• Intestine is somewhat
degenerate
EVOLUTION
• Hairworms are related to roundworms, thorny-headed worms,
kinorhynchs, and rotifers
• Originally classified as the descendants of scalidophorans – a
group that includes several related parasitic phyla
• Spread to different ecosystems with their hosts.
• The classification of hairworms is changing because of a new
phylum, under which nematomorpha would be a class, and
gordioidea and nectonematoidea would be subclasses.
LIFE CYCLE
EGGS AND LARVAE
• Female Nematomorpha can lay up to 10 million eggs in
their lifetime
• Eggs are fertilized internally and then laid along aquatic
plants in a long string of millions of eggs
• Once fertilized, the eggs mature into larvae after 2-4
weeks
AN UNWANTED PASSENGER
• Hairworm larvae are often consumed by bottom feeders
• The larvae, once ingested by this host, “encyst” themselves in a
protective barrier
• Once encysted, the hairworm can survive for up to a year in
their protective barrier
• Encysted larvae wait until they can get to terrestrial hosts
• Larvae require a terrestrial host for further development
FINDING THE RIGHT HOST
• If the paratenic host dies or is eaten the larvae either encysts in
the new host or de-cysts and tries to get eaten again
• The most common form of transfer from water to land is through
aquatic insects
• insects ingest the hairworm in their own larval form before
metamorphosis, when they gain wings and leave the water
SAFE HOUSE
• Once inside the cricket, larvae de-cyst, penetrating through the
stomach and into the body cavity, and begin absorbing nutrients
through their skin
• The only energy used by Nematomorpha while inside the cricket
is for development - no other function is completed here
• All other functions are performed outside their hosts, allowing
them to develop almost fully before leaving
KAMIKAZE WORMS
• In later stages of development, the juvenile releases chemicals
into the system of the host which alters brain functions
• Once these chemicals are released the hosts behave erratically,
moving into unusual environments and occasionally jumping into
water
• Once the developed hairworm senses liquids surrounding the
host it then exits, returning to its natural habitat to live as an
free-moving life form
• The growth period only takes between 4-20 weeks in total
THE END
SOURCES
•
Bolek, M. ,. E. A. (2011, August). Hairworm biodiversity survey. Retrieved from
http://www.nematomorpha.net/Nematomorphs.html
•
Films, V. B. (2002). Hairworm leaving a cricket. Retrieved from
http://www.nature.com/nature/journal/v440/n7085/extref/440756a-s2.mov
•
Hanlet, B. (2002, June 1). Morphometric analysis of nonadult characters of common
species of american gordiids (nematomorpha: gordioidea). Retrieved from
http://digitalcommons.unl.edu/cgi/
•
Long, B. (2007, April 25). Nematomorpha. Retrieved from
http://www.drbilllong.com/AnPhyla/NematomorphaII.html
•
Shapiro, L. (2008). Nematomorpha. Retrieved from
http://eolspecies.lifedesks.org/pages/30214