Book : Zoology
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Posted by: CHELSEA
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Writer CHELSEA

Animals

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Introduction

Animals Ovipary – is the development of embryo inside the egg but outside the body of female. The phenomenon occurs in egg laying animals. Vivipary – is the fertilization and development of embryo occurring inside the body of female. Placenta is present. Young ones are directly given birth. E.g. Metatherian and Eutherian mammals. Ovovivipary – female allows the development of embryo inside the body but do not provide any other extra nourishment as the placenta is absent. E.g. shark, rattle snake, marsupials etc.

Reproduction

Sex: Monoecious or bisexual or hermaphrodite – one organism consists of both sexes in it. E.g. flatworms, annelids Dioecious or unisexual – Each organism either male or female sex. E.g. Roundworms, arthopords etc. Sexual dimorphism – male and female animals can be distinguished morphologically (externally). E.g. lion &lioness, man & women etc. Protoandry – Male reproductive organs mature before female organs Protogyany – Female reproductive organs mature earlier than male ones. Development: Direct: In this, there is no larval stage and newly born young resembles the adult. Indirect: Young ones quite differ from adult ones and called nymphs or larvae. They lead independent life and undergo metamorphosis to become an adult. Sinuses – cavity filled with blood Book lung – is a primitive, leaf like & flatted type of lung found in class arachnida of phylum arthopoda. E.g. in spider, scorpion etc. Malphagian Extretin in mosquito, coaxial glands (attached to leg and body in arthopods).


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