Paragordius obamai

Its so sad to have to say goodbye to such an interesting species. If you were intrigued by the facts presented in this blog please join me for one last journey. 

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“A new species of Gordius (Phylum Nematomorpha) from terrestrial habitats in North America”

Contributors: Christina Anaya1, Andreas Schmidt-Rhaesa2, Ben Hanelt3, Matthew G. Bolek1 (1)

Christina Anaya and her peers decided to conduct research on the species of Gordius. The purpose of this research was to determine how the morphology (of both adult and non-adult stages), reproduction, and other characteristics of this species contributed to the environment in which the lifestyle was carried out. They used this research to compare the uniqueness of the Gordius species from the other species that fell under the Nematomorpha phylum as well. They hypothesized that, “The consistent occurrence of this gordiid in terrestrial habitats, along with its distinct egg morphology, suggests that this new species of hairworm has a terrestrial life cycle.”

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A few keywords you may need to know before diving into this literature are as follows:

1.Paragordius/Gordiida- freshwater horsehair worms of the Nematomorpha Phylum 

2.Nematomorpha- a small phylum that comprises the horsehair worm; possession of a true body cavity, gonads discontinuous with their ducts, and an atrophied digestive tract in the adult

3.Terrestrial- of or relating to the earth or its inhabitants

4.Cysts-  a closed sac having a distinct membrane and developing abnormally in a cavity or structure of the body

5. Larvae – the active immature form of an insect, especially one that differs greatly from the adult and forms the stage between egg and pupa, e.g. a caterpillar or grub.

In this research the worms were collected from terrestrial environments and observed for any morphological similarities and/or differences. The male, female, and non adult (cysts and larvae) forms were studied with microscopy. As a result, it was discovered that the larvae development showed something not seen before in this species. The fully developed larval eggs had space between what appeared to be an egg shell and the thick inner membrane.

The introduction of the thick membrane is unique to the Nematomorpha phylum as opposed to the thin membrane that most are accustomed to. Another unique characteristic is that the adult males have a unique row of bristles on the ventral inner side of each tail lobe and a circular pattern of bristles on the terminal end of each lobe, which distinguishes them from all other described North American species of Gordius. The egg string, larval, and cyst morphology of this new species conform to previous descriptions of non-adult hairworm stages. However, only one report of this species showed egg string depositing in a terrestrial habitat. With the small amount of evidence showing that there is evidence of terrestrial hair worms and a small portion showing larvae with the thick membrane; the research hypothesized that the introduction of this new characteristic may have some contribution to the terrestrial habitats of this species. Further research may be helpful in obtaining a conclusion on if the terrestrial habitat is an event of the thicker membrane beneath the shell layer of the larvae. 

These findings are unique to this species due to the introduction of the thicker membrane that no other species within the phylum carry. They feel that this introduction may have some form of contribution to the terrestrial invasion that this species demonstrates. I believe that these findings just go to show that new adaptations come and are passed on for the better of a species. Evolution is inevitable, evolution is mostly beneficial, and evolution can explain the why’s and how’s to many of the changes we see today across all species. Theodosius Dobzhansky once said, “Nothing in Biology Makes Sense Except in the Light of Evolution.” I truly believe this quote shows how much impact evolution has in the world today. 

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Citations:

1. Anaya C, Schmidt-Rhaesa A, Hanelt B, Bolek MG (2019) A new species of Gordius (Phylum Nematomorpha)
from terrestrial habitats in North America. ZooKeys 892: 59–75. https://doi.org/10.3897/zookeys.892.38868

Within Nematomorpha there are two orders the Gordiodea and the Nectonematoidea. These two orders are very similar in their ways of life. The biggest similarity is how they effect hosts; both temporarily paralyze their hosts until they are complete in development. Upon exiting the hosts can die prematurely and the nematomorphs go one to live and reproduce. Surprisingly, this isn’t the only species to do such work. In the figure below you can see that Nematomoprha and Nematoda are closely related. But how close can they really be? 

(2)

According to Wright, J.; the phylum Nematomorpha contains two orders; Nectonematoidea and Gordiodea, both of which are parasitic as larvae and free living as adults. These two orders also have very similar habitats that include marine/fresh water, coast shore, and damp/moist terrestrial areas.(1)

However, the two orders dp have different blastocoeloms. Nectonematoidea have a spacious blastocoelom and Gordiodea have one filled with mesenchyme. (1) The two also inhabit two different types of organisms as parasitic larvae. Gordiodea inhabit terrestrial organisms and make their way back to the water where Nectonematoidea inhabit aquatic animals and typically remain in the water. 

As shown above and stated before, the closest taxa to Nematomorpha are the Nematodes which share a node making them sister taxa. Larvae from both are ingested by the host organism in which they exhibit parasitic lifestyles. The feeding of the larvae on the hosts causes premature death in hosts from both phylum, from here the larvae molts and becomes adults to escape the host and become free living adults. Moist conditions/environments are typical in both Nematomorphs and Nematodes. 

In a study conducted by Bleidorn,C. all cases studied, nematomorphs were the sister group to nematodes, appearing within Ecdysozoa as described in Garey (2001). Removing sequences with the longest branches (Neetonemu, AscariJ, Mermis) in any combination had no effect on the tree topology. (5)

Like nematodes, the nematomorphs have only longitudinal muscle and lack body segmentation. The appearances of the two are strikingly similar that without deeper research many confuse the two to represent one species. (4)

Depicted below is a Nematode exiting a grasshopper (A), and a Nematomorph exiting a black beetle (B).

A. (3)

B. (3)

The relationship between Nematodes and Nematomorphs is more than physical appearance(morphology) or anatomy, but also very similar in the development processes, physiological processes, and by way of actions in how they infect hosts in order to survive in a world where they would “naturally” be the prey of larger organisms.

 

 

Citations: 

1. Wright, Jeremy. “Nematomorpha (Horsehair Worms).” Animal Diversity Web, https://animaldiversity.org/accounts/Nematomorpha/.
2. Blc.arizona.edu. (2019). PhylEcdy.htm. [online] Available at: http://www.blc.arizona.edu/courses/schaffer/182/PhylEcdy.HTM
3. Cranshaw, W. (2019). Weird Worms: Horsehair Worm and the Grasshopper Nematode – 5.610 – Extension. [online] Extension. Available at: https://extension.colostate.edu/topic-areas/insects/weird-worms-horsehair-worm-and-the-grasshopper-nematode-5-610/ 
4. Holt, J. and Iudica, C. (2019). NEMATOMORPHA. [online] Comenius.susqu.edu. Available at: https://comenius.susqu.edu/biol/202/animals/protostomes/ecdysozoa/nematomorpha/nematomorpha-description.html. 
5. Bleidorn, C., Schmidt-Rhaesa, A. and Garey, J. (2005). Systematic relationships of Nematomorpha based on molecular and morphological data. Invertebrate Biology, 121(4), pp.357-364.

Welcome Back!!!

Earlier I mentioned the fact that hairworms cause their hosts to commit suicide unwillingly so that they can continue their life cycle and reproduce. Here’s why and how they do such. 

These worms can grow up to a foot long, but to get to that point, it needs a house cricket or grasshopper to be its host to do such growth. (Jones 2015).

In the picture below you will see that once in, the hairworm coerces the insect into the nearest body of water as opposed to running away from it.  (Jones 2015)

(Source: http://www.bbc.com/earth/story/20150316-ten-parasites-that-control-minds)

First, a tiny horsehair worm larva is eaten by the larva of another insect, such as a mosquito or mayfly. Once this emerges from the water, a cricket or grasshopper will snatch it up. Then the horsehair worm begins to develop inside the insect (Jones 2015).

This isn’t the end; the worm’s final stage of development takes place in water. The cricket wouldn’t normally swim, or even hang out near water, so the worm must figure out a way to get into the water while growing in the host. (Jones 2015).

By altering the functions of the cricket’s nervous system, the cricket jumps into the water and drowns itself, allowing the horsehair worm to emerge and reproduce for a repeated cycle. (Jones 2015).

With regards to the hairworm proteome reaction during the expression of the water-seeking behavior by the host, many of the identified proteins are linked to protein biosynthesis (pC, pD, pP, pA1), to the release and secretion of neurotransmitter (pA, pG), to functions on the CNS (pB, pG, pI, pM, pQ, pY), and to endopeptidase inhibition (pZ)(Biron et. al 2005).

Biron and his group of researchers observed that the parasite produced ‘host-like’ proteins, illustrating a case of a molecular mimicry (Salzet et al. 2000; Taylor et al. 2004). More specifically, an overproduction of two proteins (pQ and pY) acting directly in the development of the CNS. (Biron et. al 2005).

MALDI-TOF signals suggest that these two proteins are synthesized by hairworms but are mimetic to proteins observed in the class Insecta (Biron et. al 2005).

From the outside, you wouldn’t be able to tell if a cricket had been infected, but neurologically, the worm is in control (Jones 2015).

This form of mimicry allows the host insect to be infected without realization of the being taken over. The hairworm can call the shots while the host believes they are acting on their own instinct.  

(Source: https://www.wired.com/2014/05/absurd-creature-horsehair-worm/)

 

 

Citations: 

Jones, L. (2015). Earth – Ten sinister parasites that control their hosts’ minds. http://www.bbc.com/earth/story/20150316-ten-parasites-that-control-minds.

D. G. Biron, L. Marche, F. Ponton, H. D. Loxdale, N. Gale´otti,L. Renault, C. Joly and F. Thomas (2005). Behavioural manipulation in a grasshopper harbouring hairworm: a proteomics approach. doi:10.1098/rspb.2005.3213

Today we will be learning about the anatomy and functions of the Paragordius obamai species!

Here below you can see the overall juvenile structure, at the top(Figure 15.17), and the transverse section, at the bottom(Figure 15.16), of the Paragordius obamai. 

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Because this species doesn’t need to reproduce sexually, and there is no need for the external sex organs to be present. The females do carry ovaries (Figure 15.16B), and the males* do have internal testis organs (Figure 15.17A); however remember that the Paragordius obamai females can reproduce without the need for male species fertlization. (1)

Paragordius obamai is a free-living organism that lives in aquatic areas or in damp soil; the movement of these animals is based on the constriction of their longitudinal muscles that are composed within the body, and therefore there is an absence of locomotion cilia or flagella as movement via those organs isn’t necessary(15.16A). (1)

Depicted above in Figure 15.17B, the larvae bear a protrusible probos­cis which bears spines. This feature is for the use of feeding/sucking nutrients. As larvae this species is parasitic in the environment; it isn’t until maturation that the species becomes free living and the anatomy of the animal is altered to reflect that of similarity to Figure 15.16A. (1)

The Phylum Nematomorpha is divided into two classes; the Nectonematoida class, and the Gordioida class. The Paragordius obamai falls under the Gordioida class. (1)

Maybe you can notice that the circulatory, respiratory and excretory systems are absent among these organisms, and that the necessary organs for these systems aren’t there in entirety; this is due to the pseudocoel being a mostly fluid-filled body cavity in addition to being filled with parenchyma cells (Figure 15.16B). (1)

Some of these structures have similarities to the Phylum Nematoda (absent respiratory and circulatory system, unsegmented body, longitudinal muscle, and etc.) , Phylum Kinorhyncha (absence of respiratory and circulatory systems and juvenile cuticle molts), and the Phylum Priapulida (cuticle molts and a pseudocoel body cavity). (1)

It appears that this new found species may have adapted/inherited all the favorable conditions of those closely related to enable its survival without compromising a lifestyle for the missing/removed features.

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                                                                   Paragordius obamai 

A species of nematomorphs that was named after the 44th president of the United States. Yes, President Barack H. Obama has a nematomorphs species named in his honor! Why you ask? This is because it was discovered in Kenya, where his father was raised. (1)

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Nematomorphs are also known as hair worms; this species can be considered parasitic. They start as larvae that are living inside arthropod hosts upon maturation they become free swimming adults. How is that possible? They induce their hosts to commit suicide by “encouraging” them to jump into the water. Hair worms typically sexually reproduce via “Gordian knots.” (1)

The Paragordius obamai species however, is found in faster moving water that makes mating more difficult. This change has promoted evolution of parthenogenesis. This species is composed mainly of females. P. obamai has completely given up on males. (1) Sexual reproduction is no longer needed for this group of organisms as it is already difficult to find a mate in their “newly explored” environment. 

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