1. Sex Determination:
* Most barnacles are hermaphroditic, meaning they have both male and female reproductive organs. However, they can't self-fertilize.
2. Fertilization and Larval Development:
* Cross-fertilization: Barnacles release sperm into the water, and it's picked up by nearby individuals. This sperm travels through the water column and enters the female's reproductive tract.
* Internal fertilization: The eggs are fertilized internally and develop into larvae.
* Nauplius larvae: Barnacles release free-swimming larvae called nauplii. These larvae are microscopic and resemble tiny shrimp.
3. Metamorphosis and Settlement:
* Cyprid larvae: Nauplius larvae go through several stages and eventually develop into cyprid larvae. Cyprid larvae are the final larval stage and are more complex than nauplii. They have a distinctive eye and sensory hairs.
* Settlement: Cyprid larvae swim in search of a suitable substrate (rock, shell, boat hull, etc.) to settle. They use their sensory hairs to detect suitable surfaces and use their antennae to attach.
* Metamorphosis: Once attached, the cyprid larvae undergo a dramatic metamorphosis, transforming into the familiar barnacle form.
4. Reproduction and Growth:
* Adult barnacle: Barnacles can live for many years and reproduce multiple times.
* Growth: They continue to grow and add new layers to their shell.
Some interesting facts about barnacle reproduction:
* Barnacles are broadcast spawners, meaning they release their sperm and eggs into the water.
* Some species of barnacles have penis length that can be several times their body length! This is due to the need to reach neighboring individuals to fertilize their eggs.
* Barnacles are considered keystone species in some marine ecosystems, meaning their presence has a significant impact on the surrounding community.
Let me know if you have any more questions!