Gametes are non-motile in blue-green algae and red algae.

Blue-green algae, also known as cyanobacteria, are a group of photosynthetic bacteria that are found in various aquatic environments. They are prokaryotic organisms and do not possess true nuclei. Blue-green algae reproduce asexually through cell division. They also have the ability to reproduce sexually, forming specialized cells called heterocysts that produce gametes.

On the other hand, red algae are a diverse group of eukaryotic algae that are predominantly found in marine environments. They are multicellular organisms and have distinct cell structures. Red algae reproduce both sexually and asexually. Asexual reproduction in red algae occurs through the formation of spores. Sexual reproduction involves the formation of gametes, which are produced in specialized structures called conceptacles.

Non-motile gametes:

1. Blue-green algae:
- In blue-green algae, the gametes are non-motile, meaning they do not have the ability to move on their own.
- The non-motile gametes are typically released into the surrounding environment, where they rely on external factors such as water currents or other organisms for dispersal.
- Once the gametes encounter each other, they fuse to form a zygote, which develops into a new organism.

2. Red algae:
- Similar to blue-green algae, the gametes of red algae are also non-motile.
- The non-motile gametes are typically released into the water, where they rely on external factors for fertilization.
- Red algae have a complex life cycle that involves alternation of generations, with the production of both non-motile male and female gametes.
- The male gametes, known as spermatia, are small and non-motile, while the female gametes, known as carpogonia, are also non-motile and remain attached to the parent organism.
- After fertilization, the carpogonia develop into structures called cystocarps, which contain the zygotes. The zygotes develop into carpospores, which are released into the water and eventually grow into new individuals.

In summary, gametes are non-motile in both blue-green algae and red algae. These organisms rely on external factors for the dispersal and fertilization of their gametes, which is an important aspect of their reproductive strategies.