Transcript

I'm at Wonga Point Bateau Bay

Today we are going to be looking at rock platform ecology

This platform has a variety of habitats.

There's flat rock, there are boulders and there are rock pools.

The different habitats means that there's a really high diversity of plant and animal species for us to have a look at.

There are three main zones on the rock platform. The low tide zone, mid tide zone and the high tide zone.

The low tide zone is closest to the ocean and covered by sea water for most of the day- it has the most diversity of species.

The mid tide zone is quite long at Bateau Bay and can be seen here in the video.

The high tide zone is the driest part of the platform and exposed to the air for long periods of time and can be identified here at the bottom of the cliff.

With the changing tide the animals and plants need to cope with different conditions.

Sometimes the rock platform is covered in water and sometimes it's very dry.

One of the adaptations for animals to cope with water loss is to be be able to hide in crevices and underneath cracks to avoid desiccation

Every divot or hollow in the rocks is used as shelter and allows these species to retain moisture.

The Chiton here has eight plates in its body to help it take the shape of the hollow.

This crevice is also sheltering a number of different species. Notice the clumping together of these Black Nerites- they too are retaining moisture by bonding closely together.

Another difficulty of living on the rock platform is having to be able to cope with the harsh waves

So animals and algae that live on the rock platform need to have adaptations to either help them to hold on to the rock closely or to be able to move with the waves.

So if you have a look at the algae that are in this rock pool you can see they're flexible so that they can move with the waves.

This one here is Neptune's necklace and we’ve also got a nice Pink Coral Algae in here.

If we look inside the rock pool you can see the pink coralline algae on the left, in the middle is Sargassum weed and on the right Neptune's necklace.

These Sea Anemonies on the top of the rock pool are also adapted to the harsh waves.

They have a special attachment called a basal disc that helps them hold on to the rocks.

So the animals that are living in this part of the rock platform have different levels of ability to be able to hold themselves closely to the rocks

and suction down.

If you have a look at this Blue Periwinkle here it's probably got the least amount of group. If I move it with my finger I can unseal him quite easily.

This barnacle here has got the highest grip- it's cemented to the rock if I push it -it's not going anywhere

This limpet I can feel a little bit of movement in there and I could probably pry it off with a knife but pushing it there's only a tiny bit of movement

Animals on the rock platform feed in different methods. Some animals grazers, some animals are predator and some animals are scavengers.

Over here we've got a really good example of a predator. This is an oyster borer and it's feeding on

Barnacles. It bores into the barnacle shell and uses an enzyme to help break up its prey.

Barnacles are cemented to the rock and unable to move. The oyster borers is in this location can have their feed and then move back to the crevice

where it's nice and moist.

The grazers are actually searching for the algae living on top of the rocks. Inside their bodies they've got a sharp tongue called a radula which they are

able to scrape across the top of the rock to get their feed.

Looking at the bottom of different molluscs allows us to decide if it's a herbivore or a carnivore.

On the left is an Oyster Borer and its shell shape is pointed while on the right is a Zebra Periwinkle

his animal grazes on algae and its shell shape is more round.

This is a Turban Shell and although the animal inside has died you can see the round shape that shows it's a grazer

Here are some more examples of carnivores. These are both Whelks- notice the pointy shape showing that they are a carnivore.

The one on the left is a Triton and the one on the right is called a Cartrut.

Anemonies are an interesting predator. Around their central mouth they have rings of tentacles with ends that contain stinging cells

to immobilise their prey. The tentacles help put food into their mouth.

In this part of the rock platform you can see one of the main filter feeders which is the Cunjevoi.

They have a siphon in the middle of their body that allows them to intake water. From this they are able to get plankton, which they

feed on.

Here is another predator of the rock platform- this is a Sooty Oyster Catcher and a threatened species at Bateau Bay.

They like to feed on molluscs and Cunjevoi. To help protect these and other water birds, visitors need to be aware of bag limits for Marine

Invertebrates. This will ensure a constant food source and keep the ecosystem in balance. Also remember to be responsible when fishing.

Clean up any tangled line and take home any plastic bait bags.