 Well, next topic is the sexual reproduction in invertebrates. So sexual reproduction, as we are familiar with, has two individuals. One of the parents produces sperms and the other eggs. There is fertilization and then the individual, the zygodes form which becomes deployed. So this is something like we have studied in the Mucleph modules previously. Now let's see how the sexual fertilization is done in the Mucleph and invertebrate groups. In the Unidarians, this is an obelia, this is an obelia colony. On top of this, there are polyps which are only for food taking. And its tentacles and they take the food in. And there is a formation of medusae. This is another part of the same colony. Now these are the medusae. Now these medusae have reproductive organs. And this is one of the medusa that produces eggs as a male and the other female. It produces the eggs, the sperm that you write together. There is a fertilization and there is a swimming larvae produced. And then it attaches itself to the underlying water or underwater. And then this colony develops. So this is the process which occurs in the Nidarians. There are flat worms. Flat worms, they are hermaphrodites. Or having both male and female sexes. And they typically reproduce both sexually and asexually. The majority of the sexual reproduction is through cross fertilization. Where both individuals fertilize each other. So this is that occurs in flat worms. And the same process is observed in polykeets. Like the examples of polykeets are earthworms. So they come together and then they exchange their sperms. So the polykeets species normally have separate sexes. While most oligokeets are hermaphrodites. In one individual, both sexes are there. In hermaphroditic species, each individual has both male and female sex organs. Which we have the example of earthworms. Then, archipods have a great diversity. There is a lot of diversity in this. In terms of sexual reproduction. A few species of insects such as honeybee reproduce parthenogenetically. Which we have understood in detail. That the eggs develop without fertilization. And in this, they are deployed. Deployed individuals. And a few species of insects. We have to quote the example of bees. In the bees, some individuals may or may not be fertilized. If they are not fertilized, they will remain haploid. And the individuals we call them as the drones. And some of these individuals become kings. And this king produces only mitotical sperms. Whereas the deployed individuals develop into the queen. The queen's size increases. There are two deployed individuals in this. If the deployed individuals develop into new individuals, they will become royal jellies. And if they do not become royal jellies, they will remain female workers. This is a very interesting phenomenon in these earthworms. Well, all known terrestrial earthworms are dioceses. Diocese means that they have different sexes. Different individuals. And they use internal fertilization. Now, once the eggs are fertilized, the females usually lay the eggs and continue developing outside the mother's body. And if fertilized, the eggs internal fertilize. Or they come out of the body and then they develop into the individual. Now, most male terrestrial earthworms they produce waterproof, that is waterproof, sorry. Yes, waterproof sperm packets, which we call sperm metaphors. Now, sperm metaphors, which are female, they take them into the bodies. They go into the bodies. And these are the sperms. Then they fertilize the eggs. Now, most earthworms, they lay eggs, but scorpions, because this is also an earthworm group of earthworms, and in these, in scorpions, there is oviparity. So, oviparous, as a condition, in which the fertilization is internal, and these eggs develop internally. And these scorpions, then they lay young ones. But directly with the individual or with the female, they don't have contact. They just, that is develop within the cavity. And then, when the young ones, which are hatched out of the eggs, they come out of the body. So, this is a lot of variety. We have quoted a few examples here. But normally, in the earthworms, there is a lot of variety of this sexual reproduction. But basically, it is the same. The sperms and eggs, they come together, proliferation occurs, and the zygote develops. And this zygote, then changes undergo a long series of processes. Or ultimately, a complete individual is formed. And then, it hatches out of the egg and then grows at the expense of food. And then, it becomes adult. So, this is the sexual reproduction in invertebrates.