Sarah Berube Naomi Demers-Agterberg Mike Downing Miranda Downing NEMATOMORPHA
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.
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) PLACE IN HISTORY
CLASSIFICATION Domain: Eukarya Kingdom: Animalia Phylum: Nematomorpha Classes: Gordoida and Nectonematoidea Species: 240
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. GORDIOIDEA AND NECTONEMATOIDEA
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. Intestine is somewhat degenerate Larval Hairworm
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.
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
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