Monday, October 11, 2010

Water Bear (Tardigrada) -- Zachary Kaye

Introduction: The water bear is classified under the phylum of Tardigrada. They were discovered by an amateur microscopist in 1773, and for a while, scientist had trouble trying to fit it into their classification system. The fact that they were given their own phylum, suggests that they are not closely related to any other animal. There are over 100 species of water bears, and they are all very similar and hard to tell apart. Water bear’s can be found virtually anywhere on earth, from the top of the Himalayas, to the hottest deserts. The water bear can be found right in your backyard, and is the only living animal that is able to survive the vacuum of space. (Challis)

Anatomy: The water bear is composed of a head, body, and a tail-like structure. It has eight legs, each with claws at the end of them. The water bears mouth contains sharp pointy objects called stylets, which they use to bite into moss and algae.

Form and Function: Water bears feed primarily on the fluids from animals and plant cells, such as moss. They do this by either sucking on the plant, or eating it. Water bears also eat microscopic animals such as nematodes or rotifers, and excrete the waste out of their rectum. If conditions become bad enough for the Water bear to the point where it could die, it goes into a state of suspended animation, otherwise known as an “antibiotic state”. It can stay in this state until conditions improve. The water bear has no predators, making its survival rate increase even more. The water bear is very interesting when it comes to reproduction. There are a couple of ways it can perform this task. The first is that the male can place his sperm into sperm-storing organs in the female. The second is that the female can insert a special structure into the male and grab the sperm from the male’s body. A few species are parthenogenic and capable of producing young without mating. In some species, individuals have reproductive organs of both males and females. However, most water bears are thought to lay eggs. (FCPS EDU) (Cook)

Impact on the World/Humanity: Water Bears do not seem to really help or hurt people. They spend all their time in mosses, lichens, and water. They do help with eating and breaking down these plants. (FCPS EDU)

Journal Article Review: The main point from the review is that the water bear is not very widespread in terms of people’s knowledge of them. If you were to ask people if they have ever heard of an animal with the characteristics of a water bear, chances are they would say no. However, the water bear is one of the most fascinating and most unknown animals in the world. The review says that one of the main reasons for the lack of knowledge on water bears is their size. This makes it hard to learn about them in detail, especially since they walk on their legs, and when viewing them from a microscope, you are looking at their back. I think that the author is trying to say that if more people were to learn about the water bear, it could become an animal that we could learn about in great depth. (Mach, 2000)


Challis, S. (n.d.). Tardigrades. Retrieved from

FCPS EDU, Initials. (n.d.). Water bear. Retrieved from

Cook, J. (n.d.). Water bears: tardigrada - behaivor and reproduction. Retrieved from

Journal Article Review: Mach, M. (2000, June). The incredible water bear. Retrieved from

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