There is a lot to see underwater. Even unknown things. It can also happen that you don't see what is going on directly.
Here are some examples. The video was created during many of my dives 2024 in Indonesia (Raja Ampat) and the Philippines on Romblon, Anilao and Tubbataha.
You can see the video in full screen. To do this, you have to click on the bottom right of the video:
Horn siliceous sponges are very often seen when diving. They are not plants, but animals.
Sponges are dioecious or hermaphrodites that can reproduce sexually or asexually. The sperm look like clouds of mist and, after being deposited in the water, are swirled into the collar-flagellate chambers by neighboring sponges, from where they are transported into the mesohyl to an egg cell. A larva develops from the egg cell, with different types of larvae occurring.
Further information: Wikipedia: Sponges
Sea cucumbers are usually hardly noticed when diving. But they sometimes have a very special behavior.
The sea cucumbers are dioecious and release their sexual products directly into the sea water. Within a bay, this usually happens synchronously. To do this, they stand upright with their front end and release a whitish (sperm) to yellowish (egg cells) fluid at the tip.
Their bilaterally symmetrical larvae live planktonic and are called auricularia. In addition to sexual reproduction, many sea cucumbers can also reproduce by division.
Further information: Wikipedia: Sea cucumbers
Nudibranchs have a very high reproductive potential. Depending on the species, each animal lays 300 to 900 eggs three times a year. Some water snails and all land snails are hermaphrodites, each animal lays an egg packet after mating.
The egg packets are often found as very beautiful-looking bands that are attached to the sea floor.
Additional video: Nudibranchs
Squid usually mate in large schools, which in some species can reach considerable sizes. After mating, during which the male pushes a spermatophore into the female's mantle to fertilize the eggs, the eggs are laid in long gelatinous tubes on stones and plants.
Further information: Wikipedia: Squid
