(c) Annelida
Water vascular system is the characteristic of Echinodermata.
An oviparous mother lays more eggs at one time as compared to the number of offspring a viviparous mother gives birth to at any given time. This is because of the following reasons:
Some of the modifications that help birds to fly are listed below:
Air bladder or swim bladder is a sac filled with air that regulates buoyancy in fishes. It plays a very important role in Pisces. The fishes (like Osteichthyes) where air bladder is present, it plays the following roles:
In another kind of fishes (like Chondrichthyes), the air bladder is absent. Therefore these fishes have to swim constantly to avoid sinking resulting in the consumption of a lot of energy.
To understand the above statement, one needs to define the two words – notochord and vertebra – from which the terms chordates and vertebrates are derived.
Notochord: The notochord is a flexible rod-shaped structure found in embryos of all chordates.
Vertebral column: The vertebral column, also known as backbone or spine, is a bony structure found in vertebrates. It is formed from individual bones called vertebrae.
Chordata is a phylum which is divided into three subphyla - Urochordata, Cephalochordata and Vertebrata. All the chordates at some point of their lives possess a notochord. However, in vertebrates, this notochord is replaced by the vertebral column in the adult stage. Hence, it is right to state that “All vertebrates are chordates but all chordates are not vertebrates”.
Arthropoda is the largest phylum of animal kingdom. Over two-thirds of all known species on earth are arthropods. The following are the reasons for arthropods to constitute the largest group of the animal kingdom:
The peculiar features of parasitic platyhelminthes are as follows:
Direct development |
Indirect development |
Direct development has a larval stage that is morphologically distinct from the adult. |
In indirect development, larval stage is absent, the embryo develops into a mature organism (looks like a miniature adult) without entering into the larval stage. |
A process called metamorphosis transforms the larva into a mature adult. |
In indirect development, metamorphosis is absent. |
It is found in invertebrates and amphibians. |
It is found in fishes, reptiles and mammals. |
Coelom is a fluid-filled cavity formed between the gut wall and the body wall lined by the mesodermal cells. Presence or absence of coelom is an important criterion for animal classification. The animals with bilateral symmetry are further classified into three types of groups based on the presence or absence of coelom. They are as follows:
Endoparasite - Cause infection inside the body |
Worms |
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Taenia(Tapeworm), |
Parasitic worms can cause a number of problems, including diarrhoea, fatigue, skin rash, nervousness, asthma and anaemia. |
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Fasciola(Liver fluke). |
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Ascaris(Round Worm) |
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Wuchereria(Filaria worm) |
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Ancylostoma(Hookworm) |
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Protozoa |
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Plasmodium |
Malaria |
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Entameoba |
Amoebiasis |
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Trypanosomabrucei |
African sleeping sickness |
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Ectoparasites – Cause infection within the skin |
Pediculushumanuscapitis |
Head lice |
Phthitus pubis |
Pubic lice |
(a) Operculum |
(viii) Osteichthyes |
(b) Parapodia |
(v) Annelida |
(c) Scales |
(iv) Reptilia |
(d) Comb plates |
(i) Ctenophora |
(e) Radula |
(ii) Mollusca |
(f) Hair |
(vii) Mammalia |
(g) Choanocytes |
(iii) Porifera |
(h) Gill slits |
(vi) Cyclostomata and Chondrichtyes |
Taxonomy is the study of principles and procedures of classification. Classification is the arrangement of living things according to their similarities and differences which bring order in the vast assemblage of living things in the world. A specimen can be classified in a stepwise process using the following classification categories:
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