Males have pelvic fins which bear claspers. Phylum Ctenophora i Ctenophora is a small phylum. The excretion occurs in different ways in different organisms. Body symmetry · A symmetry — Ex. Platypus oviparous Camel, Dog, Blue whale.
Some of them are given below 1. Some of these adaptations are as follows. Vagina double Examples : Marsupials. In invertebrates such as sponges, it is made up of calcareous or siliceous spicules. A complete digestive system has two openings, i. The coelom is called haemocoel.
The reasons for the success of arthropods are as follows. Cephalisation These show true cephalisation. The study of poriferans is called Parazoology. Coelomates The animals having true coelom are called coelomates. Conspicuous feature is the nose and upper lip modified as an elongated flexible proboscis or trunk. Examples: Horse Equus cabalus , wild ass Equus asinus , Zebra Equus zebra Order 18.
Streamlined body for rapid and smooth movement 2. Examples : Pig Sus , common hippopotamus Hippopotamus amphibius , camel Camelus , deer Cervus , musk deer Moschus , sheep Ovis. Symmetrical The body of some animals can be divided into two similar equal halves by one or more planes. Advancement Over Flatworms Aschelminthes show advancement over flatworms as they contain complete alimentary canal and sexes are separate. Digestive System Alimentary canal is complete and well-developed, i.
It causes loiasis disease characterised by subcutaneous smelling mosdy around the eyes. The digestive tract that has a single opening for both ingestion and egestion is called incomplete digestive tract, eg. Central nervous system is dorsal 2. Germ Layers and Organisation They are triploblastic and possess organ system level of organisation. Animals with notochord are called chordates and those animals which do not form this structure are called nonchordates, e.
It occurs in fishes, reptiles, birds, and mammals. Answer: Air bladder helps the bony fishes in buoyancy. The segmentation is external as well as internal. Diploblastic and Triploblastic Organisation Germ layers are group of cells behaving as a unit during early stages of embryonic development. General Features Some general features of phylum-Porifera are discussed below i. Digestive products are diffused into the cytoplasm. Vectors — Anopheles, Ades, Culex mosquito.
Earthworms are hermaphrodites and yet cross fertilization take place among them. Digestive System Digestive tract is the passage through which food is taken for digestion, absorption and egestion. The hard exoskeleton also reduces water loss from the body of arthropods making them more adapted to terrestrial conditions. · Bones are pneumatic bones air cavities helps to make the body light. Phylum — Platyhelminthes flat worms · Dorso-ventrally flattened body · Endoparasites, bilaterally symmetrical · Organ level of organization · Triploblastic - acoclomate · Hooks and suckers are present · Flame cells for excretions · Sexes are not separate - fertilization is internal and development is through many larval stages · Have high regeneration capacity Ex.
They develop from the neck but are not embryonic in or T n r a repetition which appears due to repeated budding As known as false segmentation or pseudometamerism. Germ Layers They are triploblastic animals. Advancement Over Annelids They have distinct head, jointed appendages for different functions exoskeleton, special respiratory organ, secrete pheromones and well-developed sense organs. Fertilisation Fertilisation in animals is of two types i. How useful is the study of the nature of body cavity and coelom in the classification of animals? Fertilization is usually internal type.
Triploblastic The animals in which the developing embryo has a third germinal layer mesoderm, in between the ectoderm and endoderm are called triploblastic animals, e. Some also can regenerate, e. It helps in maintaining buoyancy. Circulation The amoeboid cells transport food from ingesting cells to other cells. There are several parasitic species which live within the body of animals or plants, e.
For example, in earthworm, the body shows this pattern called metameric segmentation and the phenomenon is known as metamerism. It is called metameric segmentation. Answer There is a certain common fundamental feature that helps in classification of living organisms. Development is mostly indirect with larval stages called parenchymula Leucosolenia or amphiblastula Sycon. Inhabit estuaries and coastal sea. Long and protrusible, used to capture insects.