Friday was the ideal day for a Cornish rockpool ramble with warm weather and calm conditions. Over a hundred people joined the Looe Marine Conservation Group rockpool event and I’m sure other rockpooling sessions around the Cornwall were similarly well attended. (Here’s a list of what’s on this summer).

At these events I often spend so much time talking with participants and helping them to identify their finds that I end up neglecting my own child. Today, I’ve promised that I’ll stay with him and that we’ll rock pool together. We are going to find sharks, seahorses, blennies and an octopus. Or something like that!

What we do find are crabs – lots of them. We only keep each one a short time and then return it so we don’t have more than one in the bucket at a time. Our favourite is the hairy crab (Pilumnus hirtellus) – smaller than some of the others but very distinctive with its hairy claws and legs and even a hairy back. Its two claws are unequal in size, giving it a lop-sided appearance.

A large edible crab – or pasty crab as my son calls them – is wedged deep in its crevice. Its sea-green eyes watch us and its gills foam and click. We leave it safely tucked away.

A crack in a stone reveals some plump sausage-like worms. We put one in the bucket and watch it extend a frilled yellow tongue-like organ until it’s nearly as long as its body, which now also extends. These echiuran worms (Thalassema thalassemum) are not uncommon in this location but I don’t often see them as they burrow under very large boulders and in invisible cracks in the shale.

We’re big fans of sea squirts. Obviously it’s not a good idea to prod them hard or often, but we touch a couple lightly to watch the jet of water squirt out. Other sea squirts form beautiful colours and structures but don’t squirt.

Cornish Rock Pools junior explodes an oyster thief seaweed in my face. I chase a wildly flapping rockling but it slips through my fingers. We’re both having fun.

A chap with a large shrimping net tells us he netted a weaver fish earlier. The poisonous spines on their backs can give a nasty sting – it’s one of the reasons we always wear sturdy rock pooling shoes.

He sweeps the net and offers us his catch to look at. There are several small prawns and two baby wrasse. I was trying to take photos of these little fish a few days ago. Baby ballan wrasse are a stunning pale green and have large colourful eyes, but they swim quickly and are tricky to photograph. Junior and I watch the fish for several minutes.

I see everyone gathering in the distance and feel slightly guilty for not helping more, but sometimes it’s good to step back and just enjoy the rock pools with junior.