PHYLUM ROTIFERA (WHEEL ANIMALS)
• Microscopic aquatic animals. • Multicellular animals.
• Live in freshwater environments (and moist soil). • Rotifers are known as "wheel animalcules"
• They can be found on mosses and lichens. • 2,200 known species.
• Have two rings of cilia at their anterior end.
TYPES
Rotifers come in a variety of sizes, shapes, and types and are difficult to describe.
Bdelloids - Found in freshwater habitats all over the world.
Keratella - Have shells
Brachionus - Planktonic rotifers (Brachionus calyciflorus).
Polyarthra - Known as "Jumping" rotifers
SYMMETRY
Bilateral symmetry.
REPRODUCTION
Rotifers reproduce both asexually and sexually. Females reproduce asexually. Males don't eat. Instead, they drift around and produce sperm. Fertilization is internal. Some rotifers have complex life cycles dependent on environmental conditions (spring rains), where diploid females are produced by diploid eggs but where haploid males are produced by haploid sperm.
WHAT IS THEIR PSEUDOCOELOMATE BODY PLAN?
Rotifers have a fluid filled body cavity that separates the digestive tract and the outer body wall. A coelom is present but it is lined by only a mesoderm on the body wall. (See image below). Coelomates have fluid-filled cavities surrounded by both the mesoderm and the endoderm.
MY THOUGHTS
The most interesting thing about rotifera are their size. They are some of the smallest animals on Earth. Most rotifera are females, so even they are small, but they are mighty! One very cool fact is that they can dry up and shrink, but when it rains, they rehydrate and become adults. Also interestingly enough, Male rotifers don't eat. Rotifers were discovered by van Leeuwenhoek.
• Live in freshwater environments (and moist soil). • Rotifers are known as "wheel animalcules"
• They can be found on mosses and lichens. • 2,200 known species.
• Have two rings of cilia at their anterior end.
TYPES
Rotifers come in a variety of sizes, shapes, and types and are difficult to describe.
Bdelloids - Found in freshwater habitats all over the world.
Keratella - Have shells
Brachionus - Planktonic rotifers (Brachionus calyciflorus).
Polyarthra - Known as "Jumping" rotifers
SYMMETRY
Bilateral symmetry.
REPRODUCTION
Rotifers reproduce both asexually and sexually. Females reproduce asexually. Males don't eat. Instead, they drift around and produce sperm. Fertilization is internal. Some rotifers have complex life cycles dependent on environmental conditions (spring rains), where diploid females are produced by diploid eggs but where haploid males are produced by haploid sperm.
WHAT IS THEIR PSEUDOCOELOMATE BODY PLAN?
Rotifers have a fluid filled body cavity that separates the digestive tract and the outer body wall. A coelom is present but it is lined by only a mesoderm on the body wall. (See image below). Coelomates have fluid-filled cavities surrounded by both the mesoderm and the endoderm.
MY THOUGHTS
The most interesting thing about rotifera are their size. They are some of the smallest animals on Earth. Most rotifera are females, so even they are small, but they are mighty! One very cool fact is that they can dry up and shrink, but when it rains, they rehydrate and become adults. Also interestingly enough, Male rotifers don't eat. Rotifers were discovered by van Leeuwenhoek.