msc2nd komal chouhan (7).pptx reproduction in invertebrates

reproduction protozoa to echinodermets .

1. DAYANAND COLLEGE AJMER DEPARTMENT OF ZOOLOGY NAME :- Komal Chouhan CLASS:- M.s.c Zoology SemII SESSION:- 2023 -2024 TOPIC - reproduction in protozoa to echinoderms

2. P HYLUM - P ROTOZOA INTRODUCTION :- Protozoa are eukaryotic , unicellular microorganism , which lack cell wall . Includes more than 65,000 species . REPRODUCTION – ASEXUAL REPRODUCTION SEXUAL REPRODUCTION

3. ASEXUAL REPRODUCTION 1 ] BINARY FISSION :- it is the division of one individual into two approximately equal parts. its is the primary method of reproduction . This involves mitotic division of nucleus i.e. karyokinesis which is immediately followed by cytokinesis . in ciliates ( e.g. paramecium ) , during fission , meganucleus divides amitotically and micronucleus usually by mitotic division .

4. 2] PLASMOTOMY :- A special type of fission in which a multinucleate protozoan divides into two or more multinucleate daughter individuals . e.g. Pelomyxa , opalinids etc. 3] MULTIPLE FISSION :- in this , karyokinesis is not followed immediately by cytokinesis . In this , firstly the nucleus undergoes a series of division , result into a number of daughter nucleus , which usually arrange themselves at the periphery . Later the body cytoplasm divides into as many parts as there are daughter nuclei , resulting into formation of several daughter individuals. Example :- Plasmodium , aggregata .

5. 3] BUDDING

6. PHYLUM -PORIFERA(SPONGES) Sponges are classified as animals because they are : Multicellular Eukaryotic Have no cell walls Contain a few specialized cells .

7. ASEXUAL REPRODUCTION BUDDING :- External growth on sponges called a bud drops off , floats away , settles and grows . Can create a colony of sponges if it doesn’t float far . FRAGMENTATION :- piece falls off the parent and grows into new sponge. GEMMULES :- Sphere of amoebocyte surrounded by tough layer of spicules formed under stressful conditions. Survive harsh conditions that would kill adults Gemmules grow into adults when condition are favourable .

8. SEXUAL REPRODUCTION Eggs are stored inside the walls of female sponges .male sponges release sperm into the water . Sperm enter the female sponges through the water current and her cells carry the sperm to the eggs to be fertilized ( internal fertilization ). Some are hermaphrodites .

9. PHYLUM - COELENTERATES Coelenterates , are phylum of aquatic animals that include :- Jellyfish Corals Hydra Sea jellies The animals are characterized by their simple, diploblastic body structure , radial symmetry and the presence of stinging cell used for capturing prey and defense .

10. REPRODUCTION SEXUAL REPRODCTION 1. *Gamete Formation:* Medusae (free-swimming individuals) produce gametes (sperm and eggs) in their gonads. 2. *Spawning:* Sperm and eggs are released into the water column through the mouth or specialized pores. 3. *Fertilization:* Sperm fertilize eggs in the water column, resulting in a zygote. 4. *Planula Formation:* The zygote develops into a planula larva, which is a free-swimming, ciliated larva. 5. *Settlement:* The planula settles on a suitable substrate and attaches itself. 6. *Polyp Formation:* The planula develops into a sessile polyp, which is the juvenile stage of the Coelenterate.

11. ASEXUAL REPRODUCTION 1. *Budding:* Polyps produce buds, which are outgrowths of the parent polyp. 2. *Strobilation:* Polyps undergo transverse fission, resulting in a stack of disk-like structures (strobila). 3. *Medusa Formation:* Each strobila develops into a free-swimming medusa. 4. *Fragmentation:* Polyps can break into fragments, each of which can regenerate into a new individual.

12. PHYLUM –CTENOPHORE REPRODUCTION Ctenophores, also known as comb jellies, have fascinating and diverse reproductive strategies. They can reproduce both sexually and asexually: Sexual Reproduction : Most ctenophores are hermaphroditic, meaning they possess both male and female reproductive organs. During reproduction, they release sperm and eggs into the water column, where fertilization typically occurs externally. After fertilization, the zygote develops into a free-swimming larval stage called a cydippid before settling down and transforming into a mature ctenophore. Asexual Reproduction : Some species can reproduce asexually through a process called fragmentation. In this method, a mature ctenophore can split into two or more parts, each of which can develop into a new individual.

13. PHYLUM - PLATYHELMENTHIS Platyhelminthes usually live under water in sandy areas, but some can live on a host (e.g. the well known tapeworm) and others can live in soil. 

14. REPRODUCTION

15. PHYLUM -NEMATODE The Nematoda phylum is made up of all nematodes, or roundworms. Nematodes range from being parasites in plants and animals to being free-living organisms in the soil, water, and various other environments, making them one of the most numerous animals on the planet. Nematodes have bilateral symmetry, meaning that their halves mirror each other. They are also non-segmented and have tubular bodies. Examples of nematodes include hookworms, lungworms, and pinworms. The majority of nematodes are dioecious, which means that the female and male reproductive organs are in separate individuals and therefore there are distinct females and males.

16. SEXUAL REPRODUCTION In following steps : - Mate finding :- male and female locate each other through chemical signals ( pheromones ). Mating :- male use their specialized tail to transfer sperm to the female’s vulva . Sperm transfer : - sperm are transferred through a process called “spicule thrusting ”, where the male’s spicules (paired pointed structure ) are inserted into the female’s vulva . Fertilization:- sperm fertilize eggs in the female’s uterus . Egg – laying :- female lay eggs , which hatch into larvae . example – toxocara canis ( dog roundworm ), ascaris suum ( pig roundworm) MALE REPRODUCTIVE SYSTEM :- TESTIS :- produce sperm . VAS DEFERENS :- stores and transports sperm . SPICULES :- paired , pointed structure used for sperm transfer . GUBERNACULUM :- supports the spicules during mating . FEMALE REPRODUCTIVE SYSTEM :- OVARY :- produce eggs . OVIDUCT :- transports eggs to the uterus . UTERUS :- stores fertilized eggs. VULVA :- receives sperm during mating .

17. ASEXUAL REPRODUCTION 1. *Parthenogenesis*: Unfertilized eggs develop into offspring without meiosis or fertilization. 2. *Hermaphroditism*: Individuals produce both sperm and eggs, allowing self-fertilization. 3. *Apomictic Parthenogenesis*: Embryos develop from unfertilized eggs without meiosis or fertilization. 4. *Automictic Parthenogenesis*: Unfertilized eggs undergo meiosis, but the resulting embryos develop without fertilization. *Mechanisms of Asexual Reproduction:* 1. *Mitotic Parthenogenesis*: Eggs develop into offspring through mitosis, without meiosis or fertilization. 2. *Endomitosis*: Eggs undergo endomitosis, resulting in a diploid nucleus without meiosis or fertilization. 3. *Genetic Recombination*: Some nematodes can undergo genetic recombination without meiosis or fertilization. *Examples of Asexually Reproducing Nematodes:* 1. *Meloidogyne* (Root-knot nematodes) 2. * Heterorhabditis * (Entomopathogenic nematodes) 3. *Caenorhabditis* (Roundworms) 4. *Steinernema* (Entomopathogenic nematodes)

18. PHYLUM ANNELIDA

19. PHYLUM MOLLUSCA

20. REPRODUCTION IN MOLLUSCA Some have external fertilization ( tusk shells, bivalves , chiton and some gastropods ) Other have internal fertilization – a spermatophore , or sperm packet is deposited into the female via a modified arm ( cephalopods ) or penis (gastropods) . Some create a trochophore larvae which develops into a veliger ( a planktonic larva with a tiny shell ) Cephalopods lay eggs and the young develop from the yolk . Female octopus usually die after laying and guarding eggs – most likely due to starvation.

21. PHYLUM

22. REPRODUCTION IN ARTHROPODA

23. REPRODUCTION IN ARTHROPODA CONT…. Most arthropods have separate males and females and reproduce sexually Fertilization usually internal , sometimes external in aquatic species A few species hermaphroditic . ex – barnacles parthenogenesis – asexual reproduction in which new individual develops from unfertilized egg( ex . Bees , ants , aphids. Reproductive diversity one reason why more arthropod species than all the other animal species combined .

24. REPRODUCTION SYSTEM MALE AND FEMALE MALE REPRODUCTIVE SYSTEM :-

25. FEMALE REPRODUCTIVE SYSTEM

26. PHYLUM ECHINODERMATA