Echinodermatas consist of marine floor dwelling invertebrates. Their reproductive systems have evolved to a point where they can mate in such circumstances.
Sea urchins
Sea urchins reproduce sexually. They mate by simply ejecting sperm and eggs into the water surrounding them through five holes called "gonopores". The sperm and eggs meet and fertilize. They then hatch into Larvae which may take up to five years to mature.
A sea urchin's gonopores and gonads.
Sea urchins
Sea urchins reproduce sexually. They mate by simply ejecting sperm and eggs into the water surrounding them through five holes called "gonopores". The sperm and eggs meet and fertilize. They then hatch into Larvae which may take up to five years to mature.
A sea urchin's gonopores and gonads.
Starfish
Starfish sexually reproduce, though distinguishing between male and female is almost impossible. Starfish mate through free spawning, like sea urchins. The sperm and eggs are released through gonopores in the body and become fertilized in the water. Some starfish "brood" their eggs, in which the eggs are attached to either the mother or a surface. This is done when the only environment is either cold or hostile, as it gives the brood more of a chance to hatch.
Here is a female starfish with a brood of juveniles on her arm.
Starfish sexually reproduce, though distinguishing between male and female is almost impossible. Starfish mate through free spawning, like sea urchins. The sperm and eggs are released through gonopores in the body and become fertilized in the water. Some starfish "brood" their eggs, in which the eggs are attached to either the mother or a surface. This is done when the only environment is either cold or hostile, as it gives the brood more of a chance to hatch.
Here is a female starfish with a brood of juveniles on her arm.
Sea Cucumbers
Sea cucumbers produce sexually, but their gender can change as their life cycle goes on. many sea cucumbers release their gametes into the water to be fertilized, but those who change gender may have both gametes stored at the same time. In this case, the released zygote will be picked up and stored in a pouch. Some sea cucumbers brood their eggs inside themselves and then give birth through a rupture near the anus. in all cases, the zygotes develop into larvae until they reach maturity.
Mating sea cucumbers.
Sea cucumbers produce sexually, but their gender can change as their life cycle goes on. many sea cucumbers release their gametes into the water to be fertilized, but those who change gender may have both gametes stored at the same time. In this case, the released zygote will be picked up and stored in a pouch. Some sea cucumbers brood their eggs inside themselves and then give birth through a rupture near the anus. in all cases, the zygotes develop into larvae until they reach maturity.
Mating sea cucumbers.