Sebastian A. Baldauf, Timo Thu¨nken, Joachim G. Frommen, Theo C.M. Bakker, Oliver Heupel, Harald Kullmann. 2007. Infection with an acanthocephalan manipulates an amphipod’s reaction to a fish predator’s odours. International Journal for Parasitology 37: 61–65
This interesting article experimentally demonstrated a scenario where an acanthocephalan parasite exhibits behavioural modification on its intermediary host. The experiment consisted of amphipods which were either infected with acanthocephalan parasites, or parasite free and subjected them to olfactory stimulant which simulates the presence of a predatory fish. In their results, the un-infected amphipods retreated from the stimulus while the infected amphipods swam directly toward the scent. This change in behaviour is thought to be a mechanism to which the acanthocephalans use to increase the chance they will be taken up by their secondary host.
As to how the acanthocephalans actually manipulate the host behaviour, the article did not cove extensively; however, they did mention a similar situation where another parasitic species physically manipulated a nerve ganglion in its host in order to change its behaviour... creepy.
Annotated Bibliography (2 of 3)
Gary McClelland, Jason Melendy. 2007. Use of endoparasitic helminths as tags in delineating stocks of American plaice (Hippoglossoides platessoides) from the southern Gulf of St. Lawrence and Cape Breton Shelf . Fish. Bull. 105:180–188
The purpose of this paper was to test whether there were two distinct stocks of American plaice, a species of flounder, within the Gulf of St. Lawrence and Cape Breton shelf. To deliniate the stocks, the presence of different species of parasites, in this case Acanthocephalans, were used as geographic markers of the stocks. McClelland and Melendy concluded that there were, in fact, two distinct stocks of plaice within the Gulf of St. Lawrence, each with its own species of acanthocephalan parasite. Due to frequent mixing of populations, no conclusion of a distinct stock could be made for the Cape Breton Shelf.
The purpose of this paper was to test whether there were two distinct stocks of American plaice, a species of flounder, within the Gulf of St. Lawrence and Cape Breton shelf. To deliniate the stocks, the presence of different species of parasites, in this case Acanthocephalans, were used as geographic markers of the stocks. McClelland and Melendy concluded that there were, in fact, two distinct stocks of plaice within the Gulf of St. Lawrence, each with its own species of acanthocephalan parasite. Due to frequent mixing of populations, no conclusion of a distinct stock could be made for the Cape Breton Shelf.
Annotated Bibliography (1 of 3)
Holger Herlyn, Oliver Piskurek, Jurgen Schmitz, Ulrich Ehlers,and Hans Zischler. 2003. The syndermatan phylogeny and the evolution of acanthocephalan endoparasitism as inferred from 18S rDNA sequences. Molecular Phylogenetics and Evolution 26: 155–164
This article addresses the issue of how to phylogenetically classify groups within Syndermata. Although Herlyn et al. do not use the classification of syndermata, they do nest Acanthocephala within Rotifera. Therefore, when determining the phylogenetic relationships, Acanthocephala is compared with the three classes of Rotifera. By using 18s ribosomal DNA (rDNA) with several phylogenetic analyses, they conclude that Acanthocephala is a sister group to the Seisonidea rotifers, placing Bdelloid and Monogont rotifers in their own clade. They propose that, from this relation ship, the commensal life style of the seisonids gave way to the parasitic lifestyle of the acanthocephalans.
This article addresses the issue of how to phylogenetically classify groups within Syndermata. Although Herlyn et al. do not use the classification of syndermata, they do nest Acanthocephala within Rotifera. Therefore, when determining the phylogenetic relationships, Acanthocephala is compared with the three classes of Rotifera. By using 18s ribosomal DNA (rDNA) with several phylogenetic analyses, they conclude that Acanthocephala is a sister group to the Seisonidea rotifers, placing Bdelloid and Monogont rotifers in their own clade. They propose that, from this relation ship, the commensal life style of the seisonids gave way to the parasitic lifestyle of the acanthocephalans.
Pictures and the like
For some cool looking pictures of rotifers, microscopy-UK.org.uk has a great gallery of rotifers.
If you want to see Rotifers in action, there's an eight minute video that'll surely be more rotifers than anyone will want to see. check it out.
If you want to see Rotifers in action, there's an eight minute video that'll surely be more rotifers than anyone will want to see. check it out.
Fossil Record
Syndermata has a very low representation in the fossil record. This is due mainly to the fact that they are small, usually microscopic, soft-bodied animals. Until recently, fossils could only be found dated to the Holocene era, which only goes as far back as 8000 years.
In 1991, Bdelloid rotifers have been identified within fossilized amber taken from a Dominican mine. The amber from this mine is estimated to be 30 to 40 million years old.
For a more indepth read on the subject, check out the article:
G. O. Poinar Jr and C. Ricci. 1992. Bdelloid rotifers in Dominican amber: Evidence for parthenogenetic continuity. Experientia 48 : 408 -410
In 1991, Bdelloid rotifers have been identified within fossilized amber taken from a Dominican mine. The amber from this mine is estimated to be 30 to 40 million years old.
For a more indepth read on the subject, check out the article:
G. O. Poinar Jr and C. Ricci. 1992. Bdelloid rotifers in Dominican amber: Evidence for parthenogenetic continuity. Experientia 48 : 408 -410
Acanthocephala
Acanthocephala, related to the rotifers, is a clade of endoparasitic worms. These worms lack a mouth or a digestive system, instead, they absorb nutrients through their epidermis. The anterior region of acanthocephalans consists of an eversible proboscis covered in hook-like spikes which are thought to be ciliary in origin (relating to the rotifers). The mechanism used to propel and contract the proboscis is two sacs, called lemnisci, located on either side of the proboscis sac and act as a hydraulic system.
As can be seen in the diagram below, the Acanthocephalans have a unique circulatory system called the lacunar system. It is comprised of longitudinal canals through the cytoplasm of the syncitial epidermis. lateral pathways are found throughout the epidermis.
The life cycle of a typical acanthocephalan consists of two hosts: an intermediary host (usually an arthropod) during the juvenile stage, and a vertebrate host for adulthood. Unlike the Rotifers, Acanthocephalans are dioecious, requiring sexual reproduction. Eggs are laid by the female which are excreted by the vertebrate host. Organisms such as isopods and other crustaceans will pick up the eggs while ingesting the detritus. The acanthocephalan hatches and develops into a cystacanth within the intermediary host. eventually the intermediary host is consumed by the potential vertebrate host and the cystacanth infects the vertebrate, everting its proboscis and attaching to a tissue wall.
As can be seen in the diagram below, the Acanthocephalans have a unique circulatory system called the lacunar system. It is comprised of longitudinal canals through the cytoplasm of the syncitial epidermis. lateral pathways are found throughout the epidermis.
The life cycle of a typical acanthocephalan consists of two hosts: an intermediary host (usually an arthropod) during the juvenile stage, and a vertebrate host for adulthood. Unlike the Rotifers, Acanthocephalans are dioecious, requiring sexual reproduction. Eggs are laid by the female which are excreted by the vertebrate host. Organisms such as isopods and other crustaceans will pick up the eggs while ingesting the detritus. The acanthocephalan hatches and develops into a cystacanth within the intermediary host. eventually the intermediary host is consumed by the potential vertebrate host and the cystacanth infects the vertebrate, everting its proboscis and attaching to a tissue wall.
Rotifera
Rotifers are a group of microscopic organisms with sizes ranging from .1 to 1 mm in length. Their bodies comprise of three parts: a posterior foot, a trunk containing the internal organs, and an anterior head region which usually has a band of cilia spanning it's circumference, this band is called the corona.
The picture below gives a good example of the variations of body form within the phylum Rotifera.
Rotifer 'A' is an example of a Seisonid rotifer, they use their specially adapted foot to attach themselves to the carapace of crustaceans. Rotifer 'B' is a Bdelloid rotifer, these are either free swimming or creeping animals. The remaining rotifers in the diagram (C-H) are from the class Monogonta, among the wide variety of body forms in this class are free swimming (D-F) as well as sessile (G and H) rotifers.
Evident from the picture above, some of the ciliary structures have been modified into either long bristles, such as in collotheca rotifers or into thicker spike structures. These adaptations are usually for feeding purposes. In other cases, the cilia are reduced significantly.
In terms of the rotiferan life cycle, they rotate between asexual and sexual reproductive strategies. In ideal conditions, there are only females within a population reproducing through parthenogenisis. During extreme conditions, males will be developed and sexual reproduction will produce eggs which can lay dormant until ideal conditions return, starting the cycle over again.
The picture below gives a good example of the variations of body form within the phylum Rotifera.
Rotifer 'A' is an example of a Seisonid rotifer, they use their specially adapted foot to attach themselves to the carapace of crustaceans. Rotifer 'B' is a Bdelloid rotifer, these are either free swimming or creeping animals. The remaining rotifers in the diagram (C-H) are from the class Monogonta, among the wide variety of body forms in this class are free swimming (D-F) as well as sessile (G and H) rotifers.Evident from the picture above, some of the ciliary structures have been modified into either long bristles, such as in collotheca rotifers or into thicker spike structures. These adaptations are usually for feeding purposes. In other cases, the cilia are reduced significantly.
In terms of the rotiferan life cycle, they rotate between asexual and sexual reproductive strategies. In ideal conditions, there are only females within a population reproducing through parthenogenisis. During extreme conditions, males will be developed and sexual reproduction will produce eggs which can lay dormant until ideal conditions return, starting the cycle over again.
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