Mochi Isle
Tides & tide pools · Coconut CoveScience for kidsWhat causes tides, and what lives in a tide pool?
In short: The Moon's gravity tugs on the oceans, so in most places the sea rises and falls about twice a day. These are tides. At low tide, sea water left in rocky hollows forms tide pools, home to sea stars, anemones, crabs and shrimp.
How it works
The Moon's gravity gently pulls on Earth's oceans, making the water bulge out on the side facing the Moon. A second bulge forms on the opposite side of Earth too. As Earth spins once a day, a beach passes through both bulges, so most coasts get two high tides and two low tides roughly every day.
The sun pulls on the sea as well, but less strongly than the Moon. At new moon and full moon, the sun and Moon line up and pull together, giving extra-high and extra-low tides called spring tides. The Moon rises about 50 minutes later each day, so the tides shift about that much later too.
Tide-pool creatures are clever survivors. At low tide, anemones pull in their tentacles and become blobs of jelly to keep from drying out. Limpets clamp tightly onto rocks, and little fish and shrimp hide in cracks until the sea returns. Each high tide brings them fresh sea water and food.
Where to see it in New Zealand
Goat Island, north of Auckland, is New Zealand's first marine reserve, and its rock pools are great to explore at low tide. On the Kaikōura Peninsula, low tide uncovers wide rocky platforms. In a marine reserve, you must not take anything away.
Try it together
Check the tide times with an adult and go to a rocky shore at low tide. Crouch by a pool and stay still for a few minutes until creatures come out. Look but don't grab, put any rock back the way it was, keep an eye on the waves, and leave before the tide comes in.
Kids also ask
Why is high tide at a different time each day?
Tides follow the Moon. The Moon rises about 50 minutes later each day, so high and low tides also move a little later every day.
Can I take a sea star home from a tide pool?
Best not. Sea stars and other rock-pool creatures die quickly out of the sea, and taking anything from a marine reserve is against the law. Take a photo and leave them where they live.
In the game, “Tides & tide pools” is a nature card on Coconut Cove.
Your child finds this card by reaching the right place or meeting the right weather on the island, and lights it up by answering the question on the back. Tap the button below and the game shows your child which island it is on and how to find it. Mochi Isle is a browser learning game for ages 5 to 18; the main island and the daily lesson are free.
Find “Tides & tide pools” on the island ↗ All cards from Coconut Cove