Nematodes Might Outlive Us All! Quiz

Answer: Roundworms

Nematodes are a category of cylindrical, unsegmented (the body is not divided into specific segments) worm. Their body is triploblastic which means it has three layers of cells (ectoderm, mesoderm, and endoderm). Plant-parasitic nematodes are known as eelworms.

Answer: Ecdysozoa

Ecdysozoa include insects, crustaceans, chelicerata (includes sea spiders, arachnids, scorpions and horseshoe crabs), myriapods (includes millipedes and centipedes) and nematodes. This group is characterized by a molting process called ecdysis whereby a cuticle is shed for a new one. This molting process gives the group its name.

Answer: 25,000

There has been some debate about the actual number of nematode species because it can be hard to tell the difference between one species and another. Due to that fact, the number often changes depending on the source and the author. In 2013, there was a survey on animal biodiversity in the megajournal "Zootaxa" that put the number at over 25,000.

In 1993 the number was estimated at over one million which was followed by an article putting the number at somewhere around 40,000. Processes such as DNA barcoding and rarefaction curves have put the figure actually somewhere around one million.

Answer: Nearly every ecosystem on Earth

Nematodes have been able to adapt to just about any environment. They are found in fresh and saltwater, in deserts, in forests, in mountains and low regions, in polar regions and tropical regions. They've been found deep below the surface of the Earth and they make up approximately ninety percent of all animals on the ocean floor. Because of their diversity, and because there are just so many of them, they represent about eighty percent of all individual animals on Earth and play a critical role in many environments.

Answer: True

The anatomy of nematodes is fascinating. They are usually very small, the smallest being microscopic and one of the largest measuring eight meters long (found inside a sperm whale). Their bodies usually have ridges or rings. The mouth has three or six lips, with a series of teeth on the inner edges.

The tail has a caudal gland on the tip that secretes a substance allowing the nematode to attach itself to objects. The mouth structure opens to a sucking pharynx and the pharynx connects directly to an intestine, there is no stomach.

The last part of the intestine forms a rectum that expels waste through an anus, just below the tip of the tail.

Answer: Thoroughly cook meat before eating

Although washing your hands before eating is a good common practice, trichinosis is caused by eating undercooked meat and so the best practice is to ensure meat is thoroughly cooked before it's consumed. The lovely little nematode responsible for this disease is Trichinella spiralis, known as the 'trichina worm'.

This disease occurs in rats, pigs, bears, and humans. Other nematodes that are parasitic to humans include ascarids, filarias, hookworms, pinworms, and whipworms.

Answer: Androdioecy

Most nematode species have distinct females and males (known as being dioecious) but there are some species that have the rare characteristic of having both hermaphrodites and males. Reproduction is usually sexual although hermaphrodites can self-fertilize. Males are usually smaller than females and hermaphrodites and have a distinct bent or fan-like tail. Nematode species that exhibit androdioecy include C. elegans, C. briggsae, and Pristionchus pacificus.

Answer: C. elegans

C. elegans (Caenorhabditis elegans) is known as a model species because it has had its entire genome sequenced, the developmental fate of every cell determined, and every neuron mapped. This species of nematode lives in the soil and is a transparent nematode that is about one millimeter in length.

It lacks both a circulatory and respiratory system and most of the species are hermaphrodites. In 1963, South African biologist Sydney Brenner proposed using this simple organism as a model organism. The early cell division process of this species of nematode is among the most understood in the world of asymmetric cell division. Studies of this species of nematode have aided research into aging, Alzheimer's disease and sleep studies.

Answer: Latch on to boats causing damage

Free-living marine nematode species are absolutely abundant in both salt and freshwater environments and play many important roles. They feed on algae, animals, fungi, bacteria, fecal matter and decomposing organisms. Because of that, they are a factor in recycling and decomposition processes. They are also sensitive to changes in their environments as a result of pollution.

Answer: Survive an unprotected descent back to Earth's surface from space

The C. elegans species of nematode made news in 2003 when it was discovered that it had survived the space shuttle Columbia crash. They were part of a research project that was included on board and survived the re-entry back into Earth's atmosphere. Descendants of those nematodes were included in the Endeavour STS-134 mission in 2011. Nematodes have also spent time on the International Space Station and in 2018 were included in a study on muscle dystrophy during spaceflight.