1. The smallest type of sea animal would be zooplankton. These are really tiny animals, around 20-200 µm, which is about the diameter of a single strand of your hair. Some zooplankton are larvae that grow into shrimps, sponges or jellyfish.
2. The biggest sea animal is the Blue Whale! The Blue Whale is actually the biggest animal EVER (on land or in the sea). They can grow to 30 metres!
3. That is a REALLY hard question….I really like nudibranchs because they are so beautiful and elegant in the water. They are a type of mussel that doesn’t have a shell. They look like they are dancing and have the most amazing colours! There are lots of different types in Irish waters too. I saw one once when I was snorkelling in Galway.
I love sea otters too! I saw a few when I was in California a couple of years ago. When they are resting they all fold hands (paws!) to make a raft and then drift together. Sea otters are really important animals too because they eat sea urchins that can damage kelp forests when their numbers are not controlled (naturally by the otters).