1 00:00:00,880 --> 00:00:09,880 In another video we have studied sponges, and we have seen that sponges, when they are adults, do not move from place to place, 2 00:00:09,880 --> 00:00:18,879 that they have radial symmetry, this means they do not have a right and left side but are cylindrical in shape, 3 00:00:18,879 --> 00:00:28,879 and we have also studied that water is moved by special cells inside the sponge that are called quanocytes, 4 00:00:28,879 --> 00:00:34,159 and these quanocytes with the flagellum, with their tail, move the water so that 5 00:00:34,159 --> 00:00:39,920 the sponge can get food particles that are in the water. So water enters through 6 00:00:39,920 --> 00:00:45,479 the sides and exits through the top opening or osculum as we could see in a 7 00:00:45,479 --> 00:00:49,979 video. So now we're going to speak about sponge reproduction and we're going to 8 00:00:49,979 --> 00:00:57,840 see that sponges are able to reproduce asexually and sexually. So let us start 9 00:00:57,840 --> 00:01:01,140 speaking about asexual reproduction. 10 00:01:01,140 --> 00:01:04,319 Asexual reproduction in sponges usually 11 00:01:04,319 --> 00:01:07,260 happens because of fragmentation. 12 00:01:07,260 --> 00:01:09,359 Through fragmentation this means a 13 00:01:09,359 --> 00:01:13,200 sponge, as we can see in this drawing, gets 14 00:01:13,200 --> 00:01:16,719 broken. Some pieces of the sponge 15 00:01:16,719 --> 00:01:20,239 get disattached, they break. They may 16 00:01:20,239 --> 00:01:22,280 break by accident or they may break 17 00:01:22,280 --> 00:01:25,500 because the sponge itself breaks. 18 00:01:25,500 --> 00:01:30,739 So the sponge has a mechanism to break some parts of its body so that those parts of the 19 00:01:30,739 --> 00:01:32,200 body go away. 20 00:01:32,200 --> 00:01:38,659 If those parts that go away fall on a place with good nutrients, temperature, good conditions, 21 00:01:38,659 --> 00:01:46,040 etc., those species get attached and they grow and eventually they will form a new sponge. 22 00:01:46,040 --> 00:01:52,340 Of course, these new sponges that are going to form will be genetically identical to the 23 00:01:52,340 --> 00:01:53,400 parent. 24 00:01:53,400 --> 00:01:58,060 This means they will be clones of the parent sponge. 25 00:01:58,060 --> 00:02:00,780 So this is asexual reproduction. 26 00:02:00,780 --> 00:02:05,980 One individual produces clones. 27 00:02:05,980 --> 00:02:10,719 The other possibility is sponge sexual reproduction. 28 00:02:10,719 --> 00:02:16,300 In sponge sexual reproduction what is going to happen is that one sperm cell and one egg 29 00:02:16,300 --> 00:02:19,520 cell are going to fuse. 30 00:02:19,520 --> 00:02:27,219 So one sponge is going to produce many sperm cells. 31 00:02:27,219 --> 00:02:33,219 The sperm cells are actually very similar to coanocytes and they are derived from them. 32 00:02:33,219 --> 00:02:39,439 So then these sperm cells are going to swim out from one sponge and they are going to 33 00:02:39,439 --> 00:02:42,439 get inside another sponge. 34 00:02:42,439 --> 00:02:46,900 When they get inside the other sponge they will meet an egg cell. 35 00:02:46,900 --> 00:02:50,219 So fertilization is going to happen. 36 00:02:50,219 --> 00:02:56,539 Fertilization means the egg cell and the sperm cell fuse turning into one cell and that cell 37 00:02:56,539 --> 00:03:02,060 is going to divide, it is going to produce many new cells and those many new cells are 38 00:03:02,060 --> 00:03:05,080 going to form a larva. 39 00:03:05,080 --> 00:03:10,740 A larva is an individual that looks very different from the adult. 40 00:03:10,740 --> 00:03:16,520 In case of sponges the larva does not look like a sponge at all, it looks like a ball 41 00:03:16,520 --> 00:03:22,520 cells some of which have flagella okay so they have tails and with these tails 42 00:03:22,520 --> 00:03:29,240 the larva is able to swim and it is going to swim away when it finds a good 43 00:03:29,240 --> 00:03:36,259 place to live then the larva is going to transform into an adult and it is going 44 00:03:36,259 --> 00:03:42,979 to stay forever in the place that it has found okay so adults do not move larvae 45 00:03:42,979 --> 00:03:49,099 are able to swing look for a good place to live as an adult. This means sexual 46 00:03:49,099 --> 00:03:54,639 reproduction comes from the fusion of sperm and egg cells producing new 47 00:03:54,639 --> 00:03:57,639 individuals.