Parasites are one of those topics that are equal parts fascinating and disgustingly horrible; a combination that explains the popularity of the
television show Monsters Inside Me
and the dozens of bot fly maggot removal videos on YouTube.
Some recent news stories have included a man who was infected by a
tapeworm with cancer
which resulted in his
death from tumors comprised of cancerous tapeworm cells and the little boy who had a snail
growing in his knee
(strictly speaking, not a parasitic organism).
If those stories aren't enough to fuel your nightmares and phobias, allow me to introduce you to a peculiar class of parasites, the
The Myxozoa (etymology: Greek: μύξα myxa "slime" or "mucus" + thematic vowel o + ζῷον zoon "animals") are a group of parasitic
animals of aquatic environments. Over 1300 species have been described and many have a two-host lifecycle, involving a fish and an annelid worm or
bryozoan. The average size of a myxosporean spore usually ranges from 10 μm to 20 μm whereas that of a malacosporean spore can be up to 2 mm.
Myxozoans can live in both fresh and marine habitats. Early thought to be unicellular, they are in fact multicellular organisms, probably extremely
reduced cnidarians. Infection occurs through valved spores. These contain one or two sporoblast cells and one or more polar capsules that contain
filaments which anchor the spore to its host. The sporoblasts are then released as a motile form, called an amoebula, which penetrates the host
tissues and develops into one or more multinucleate plasmodia. Certain nuclei later pair up, one engulfing another, to form new spores.
These critters have also been found in frogs, birds and shrews and probably similarly live — in one stage or another — in a number of other hosts
yet to be described.
Until just the last few years, they were thought to be protozoans, specifically they were placed in the group
along with the such delightful organisms as
, the behavior altering parasite thought to infect as much as 30%-50% of
the world's human population and which are strongly correlated to a significant increase in the risk of traffic accidents.
Now for the shocker (not that shocking though, it's in the title)!
Further genetic study has revealed that they're actually a clade that should placed in the phylum
and that their closest evolutionary cousins are the
, a clade which includes among other organisms jellyfish and siphonophores such as the
Portuguese man o' war!
The above picture is taken from the article
Post - Mysterious parasite may actually be a tiny jellyfish gone awry
which came across my feed
yesterday and inspired me to do a little Internet research. On the left are several individuals of a species of Myxozoa and on the right, a jellyfish
cousin which is 2,500x larger.
edit on 2015-11-18 by theantediluvian because: (no reason given)