Rotifera (Latin: Wheel Animals)
Rotifera were first discovered or documented by a minister of religion (as I am) - by Rev. John Harris in 1696. Rotifera are the smallest species of the animal kingdom, and share the same physiology and structure of their larger human cousins. Rotifera can posses eyes, mouths and reproductive organs. To give you an idea of their size, you could find several Rotifera within a drop of water the size of this dot ( . ) The name "rotifer" is derived from the Latin word meaning "wheel-bearer"; this makes reference to the crown of cilia around the mouth of the rotifer. The rapid movement of the cilia in some species makes them appear to whirl like a wheel, as can be seen in the first video below, and is especially interesting to observe as carnivore Rotifera hunt their prey.
Rotifer cysts (dormant eggs) can remain viable for decades until the right conditions are met for birth, and are found in their thousands in every square meter of grass or earth around the world. They can be hatched by placing some dried grass in a container within sunlight and harvested after 24 hours.
Latest video links at top of page
This is a great video that shows the rich spectrum of micro organisms that can exist in just one drop of water,
including two mature Rotifers foraging and feeding on smaller microbes as several Algae Diatoms swim past.
This short video is of a mother Rotifer and her infant as they forage for food,
and gives an excellent picture of how these amazing and intricate animals move
by contracting and elongating their bodies while using their foot as a anchor point.
Testing out a new camera, I followed a classic rotifer for approximately 15 minutes,
and have made the best of it into a 30 second video - including two rotifers pouncing upon the same prey,
and excellent examples of the rotifer contracting and protracting her body.
Video of the first
Bdelloid Rotifer Habrotrocha I ever caught and videoed,that sparked my interest in these amazing and beautiful animals.
This video is of a beautiful Rotifer as she appears to be about to give birth. The video
clearly showing the contents of her stomach and digestive system.
I took this excellent video of a rotifer while testing a new video eye piece I'd just made.
I wasn't expecting to find anything, and didn't have much memory on my data chip/ It's still very interesting
One of my first Rotifer videos, before I ground my lens to remove the slight imperfections.
Still a good video to see the foot she uses to propel herself while eating
vegetation.
I have classified the Rotifera I have found, under four categories: Bdelloid, Lorica, Planktonic and Sessile.
Bdelloid
rotifers are the commonest variety found in fresh water. The term describes
their habit of moving about by extending the body, arching and extending the
head, then catching up with the foot and again extending the body. No
males have ever been observed among bdelloid Rotifera. They are all females
and produce eggs requiring no fertilization. In some bdelloids, the young
develop to maturity within the body cavity and are born live. In others,
eggs are produced and deposited in the vegetation of the pond's edge. In
either case, the invariably female offspring in turn produce eggs requiring
no fertilization and so on -- a process called parthenogenesis. In adverse
environmental conditions, bdelloid produce smaller non-gender eggs that once
hatched are around half the size as healthy female bdelloids, are themselves
sterile, living only a few days and serve as food for the healthier female
rotifer infants. Technically they are neither male or female.
A Lorica is a hard or semi-hard shell which forms the outer surface of the body of some rotifers. There is great variety in the shape of rotifer loricae, and in some species they can be ornately sculptured, whilst others have long spines and projections or blades. Semi-loricate is a term used to describe less obvious body thickenings which (along with other features) distinguish these rotifers from the bdelloids. The markings on the Lorica are frequently used in species identification.
Planktonic
rotifers swim freely in the open, usually surface, waters of the pond or
stream. They are strong swimmers, and some of the larger ones are
predaceous; most often preying on smaller rotifers.
Sessile rotifers are those which spend the main part of their lives attached to the stems of water plants, submerged tree rootlets, filaments of algae etc. and live by capturing the algae and other food organisms bought to them by a combination of their own feeding activities and the currents in the pond or stream in which they live. They are only free-swimming when newly hatched and in search of a place to settle, or when conditions become adverse and they are obliged to find another home. Almost all sessile rotifers build some kind of protective tube in which to live. Some tubes are merely the accumulation of mucous secretion which is compacted around the foot by their feeding current, and others are smooth regular tubes built by the rotifer from carefully deposited individual pellets of compacted debris.
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