Question

Fill out phylum characterists chart for phylum rotifera

Design Layout References Mailings Review View Help Table Design Layout Phy Porifera | Ctenophora Cnidarians Acoel Platyhelminthes Rotifera Symmetry asymmetrical Body Cavity Germs Layers Cephalization Segmentation Reproduction

Answer 1

This table specifies the characteristics of Phylum Rotifera.

Rotifers are microscopic,multicellular organisms which are mostly seen in aquatic environments with wel developed tissue and organ systems. These Rotifers are characterized by ciliated, rotating wheel like structure the corona on the head giving them a worm like appearance. Another important characteristic of this group is presence of mastax or jawed pharynx.

Phylum	Rotifera
Symmetry	Bilateral Symmetry
Body Cavity	Partially lined with mesoderm
Germ Layers	Triploblastic
Cephalization	Yes
Segmentation	Externally segmented
Reproduction	Asexual, Parthenogenesis
Digestive System	Complete
Circulatory System	Absent
Nervous System	Present
Excretory System	Present
Skeleton	Absent
Phylum Characteristics	Microscopic, Multicellular and mostly Aquatic

Symmetry- Rotifers possess bilateral symmetry. Biateral Symmetry means the property which can be divided into two equal/symmetrical halves on either side of a plane. Body of Rotifers is mostly cylindrical divided into head, nect,trunk and foot. The most distinct feature is presence of ciliated structure called corona on their head.

Body Cavity-Rotifers body cavity is partially lined by the mesoderm. Body is distinctively divided into four parts head, nech , trunck(body) and foot.

Germ Layers- Rotifers are triploblastic. they are protostomes having all the three germ layers ectoderm, mesoderm and endoderm. /ectoderm is the outer covering, mesoderm is the one in which the fluid filled body cavity is filled with and endoderm lines the gut cavity and such organisms are called triploblastic. The first opening of the embryonic cells develop into mouth.

Cephalization-Yes, Rotifers possess Cephalization which is a characteristic of bilaterally symmetrical animals,

Cephalization is concentration at the anterior end of sense organs, nervous system,etc. The formation of brain and head during course of embryo development and during evolution.

Rotifers have a small brain above the mastax from where a number of nerves extend throughout the body and this number changes from species to speices.

Segmentation-The body of Rotifers is externally segmented but they are not segmented internally. Trophi is characteristic organ of Rotifers and it is found in almost all Rotifers.

Reproduction- Rotifers are dioecious that means female and male reproductive organs are present in different individuals. They can reproduce sexually and few species reproduce by parthenogenesis which is an asexual method of reproduction. In this parthinogenesic species males may be present at certain times of the year only and female reproductive system consists of one or two ovaries with vitallerium gland which content the eggs with the yolk.

Digestive System-Rotifers digestive system is complete consists of both mouth and anus.

Circulatory System-There is no specialized respiratory system and some also lack circulatory system in Rotifers. In some species the fluid near the organism's membrane and body cavity forms circulatory system in Rotifers.

Nervous System- Rotifers have a small brain above the mastax from where a number of nerves extend throughout the body and this number changes from species to speices. Brain shape and size also varies.

Excretory System- Rotifers excretory system consists of two protonephridia with flame bulbs opens into cloacal bladder(urinary bladder. Excretory wastes are collected at the clocal bladder before being released by the anus.

Skeleton-Rotifers lacks Skeleton. But they have various shapes because of hydrostatic pressure in the psuedocoelom and well-developed cuticle. Cuticle maybe thick and rigid giving the animal box shape providing flexibillity and giving a worm like appearance.

Phylum Characteristics- Rotifers are microscopic,multicellular organisms which are mostly seen in aquatic environments. These Rotifers are characterized by ciliated, rotating wheel like structure the corona on the head giving them a worm like appearance. Another important characteristic of this group is presence of mastax or jawed pharynx.