At last we get to the warm-up act for the Halloween Horror that slithers in next week. But first a look to the past, and last weeks animals, were a pair of odd echinoderms, which has nothing to do with this week's body snatching issue. Hope you enjoy…

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Issue #92 - Horsehair Worm

Kingdom – Animalia

Phylum – Nematomorpha

Class – Gordioidea

Order – Gordiodidae

Family – Chordodidae

Genus – Paragordius

Species –tricuspidatus

Related Species - Horsehair worms are one of the 350 species of worm found in the Phylum Nematomorpha (1)

Range - Horsehair Worms are found across Continental Europe near or in freshwater environments

Suicide Worm

Horsehair worms are thin brown worms that, upon maturity, can reach lengths of 50cm, although width never exceeds more then a centimetre. Horsehair worms generally live in water, and gather together in mixed gender swarms to breed, with the worms tying around each other to form impressive knot like structures. It’s this behaviour that lends the name ‘Gordian’ to the species taxonomic rankings in reference to the mythical Gordian Knot of Greek Mythology (2).

Whilst anatomically simple, horsehair worms only possess a single neural cord; longitudinal muscle banks and a non functioning gut, a large number of worms from the phylum Nematomorpha have incredibly complex lifestyles. Microscopic larval worms enter insect hosts, usually a grasshopper or cricket, when it’s foraging near water. From there the worm moves to the gut where it passively absorbs nutrients and moults several times until it matures into its adult form. While seemingly sinister in behaviour, by this point the horsehair worm has done little to harm its cricket host, but this all changes when the worm is ready to emerge as an adult.

The worm begins to release chemicals, which so effectively mimic the cricket’s actual proteins that they aren’t detected by the insects immune system, that affect the insects neurological system, effectively allowing the worm to take control of its host and force them to partake in atypical behaviour (3). Often this behaviour involves heading towards a body of water and drowning itself to allow the parasitic worm, often up to 20cm long, to emerge form the cricket’s anus as a sexually mature adult.

Five Body Snatching Parasites

The adult female Jewel Wasp (Ampulex compressa) hunts cockroaches, stinging them with a mind controlling venom that allows her to lead them to a more secluded area. She then lays her eggs on the host insect, where upon the larvae hatch and devours the cockroach’s soft tissue before pupating, with the cocoon protected by the still living immobile shell of its former host.

Another wasp Hymenoepimecis argyraphaga parasitizes the spider Plesiometa argyra in its very own web. After two weeks of feeding off the spider’s blood, the larval wasp takes control of the spider’s brain and forces it to spin a repeated pattern of a single strand of silk. Once completed the wasp consumes its host and wraps itself in the silk strands before pupating in a silk armoured cocoon.

Some parasites go through multiple hosts, such as the flatworm Curtuteria australis, which parasites the New Zealand Cockle (Austrovenus stutchburyi) and an Oystercatcher (Haematopus finschi)). The worm infiltrates the cockle, where it forms cysts that feed on the shells foot, eventually wearing it away leaving the worms host immobile. Now exposed and unable to escape the cockle is consumed by the Oystercatcher where upon the parasite reproduces and finishes its life cycle (4).

So far all the body snatching parasites have killed their hosts, but the parasitic barnacle Sacculina carcini keeps its host alive for its own purposes. Attaching as a larva to a crab, female Sacculina grow in the host’s reproductive organs, feeding off the blood and tissue as it grows into a sexually mature adult. From there the parasite feeds off the sterilized crab’s blood, and grows its own eggs in the brood pouch. Upon completion, the barnacle releases the eggs and chemically commands the crab to scatter its spawn, just as it would with its own eggs.

Humans aren’t safe from this body snatching phenomenon either; the Guinea Worm (Dracunculus medinensis) causes pain in its human host, forcing them to find water to cool the infected area. Upon submerging the infected area, usually a foot, the worm emerges as a sexually mature adult ready to reproduce. Fortunately better medical hygiene and knowledge of the worm’s epidemiology has reduced the amount of people infected. As of August 2015, only 16 recorded cases of Guinea Worm infestation had been noted across the entirety of the worms range for that year.

Bibliography

1 - www.arkive.org

2 - Piper, Ross (2007), Extraordinary Animals: An Encyclopaedia of Curious and Unusual Animals

3 - Thomas, F.; et al. (2003). "Biochemical and histological changes in the brain of the cricket Nemobius sylvestris infected by a manipulative parasite Paragordius tricuspudatus (Nematomorpha)". International Journal for Parasitology 33 (4): 435–443

4 - http://www.nzgeographic.co.nz/archives/issue-103/body-snatching-parasites

Picture References

1 - http://herramientas.educa.madrid.org/animalandia/imagenes/p/paragordius_tricuspidatus.jpg

2 - https://upload.wikimedia.org/wikipedia/commons/9/9b/Spinochordodes_in_Meconema.jpg

3 - http://www.reed.edu/biology/professors/srenn/pages/teaching/web_2010/bpls_site-final/images/Screen%20shot%202010-11-21%20at%207.45.38%20PM.png

4 - http://static1.squarespace.com/static/519fc518e4b046d94a9788ad/t/52609008e4b0c0ba625390ca/1382060047783/

Well was that horrific enough for you? No! Well get ready for another foul creature next week. But until then critic, comment and suggest future issues as well as making sure you check past issues in Impurest’s Bestiary

Many Thanks

Impurest Cheese