Nematoda
Introduction:
Nematoda encompasses the roundworms- sometimes known as eelworms due to their elongated cylindrical bodies with no limbs. They are some of the most abundant and resilient animals on the planet, occurring in nearly every habitat, even extreme environments such as polar deserts, anaerobic (oxygen free) swamps, deep-sea sediments and hypersaline lakes e.g. the Dead Sea.
These organisms can be free-living or parasitic, occupying soil, fresh and marine environments, alongside some unusual environments e.g. within cracks deep in the Earth's crust
Some nematodes can cause a variety of diseases.
In the museum the nematodes can be found in the outer cabinet 4 along with the platyhelminthes.
Adaptations
Nematodes are bilaterally symmetrical (their body is a mirror image on either side). They have long round bodies which are usually tapered at each end, and posses a cuticle: a tough but flexible barrier made from collagen which is likely the reason these animals can survive such extreme environments.
Many nematodes can undergo aa process known as temporary quiescence - a state of inactivity or dormancy- when there are strong environmental stressors. This allows for long-term survival in unusually harsh environments and can take place at any stage in their life cycle before adulthood (egg, and 4 juvenile stages).
In addition, parasitic nematodes have a range of physical and behavioural adaptations to ensure their survival. In some cases this can effect the behaviour and even physiology of their host for example:
Myrmeconema neotropicum: to reach their final hosts (birds) these roundworms infect ants and move through their digestive system until they reach the belly. Which they make glow- so the ant appears bright red like a berry, tricking the host bird to eat the infected ant and passing on the parasite.
Classification:
The exact orders and defining characteristics of nematode phylogeny is not yet resolved. The most recent phylogenetic analysis report (2022) breaks nematodes into 4 main lineages/orders based off observable characteristic and genetics:
Trichinellida
All members of this order are parasites of vertebrates in their adult stage
Spirurina
These are mostly parasitic worms that inhabit soil, water and the bodies of other organisms
Tylenchina
Nematodes in this group range from free-living bacteria eating organisms, to highly specialised plant parasites
Rhabditiona
Most of the nematodes in this group are parasitic.
They have well developed exterior sensory structures
Explore the different nematode groups more with OneZoom
Museum highlights:
Caenorhabditis elegans - an incredibly important animal in the study of human diseases, considered a 'model specimen' as it shares many genomic similarities and gene systems to humans. Scientists often use this roundworm to study diseases such as Parkinson's diseases, as well as the immune system.
Gapeworm - removed from the trachea of a domestic chicken. This parasite is named so as they block the airways of the birds they infect, causing them to 'gape' as they gasp for air. The parasites are controlled by managing populations of intermediate hosts to prevent transmission into domestic fowl.
Root Knot nematodes - which attack the roots of plants resulting in large 'knots' of multiple worms siphoning off the nutreince of the plant
