Wednesday, December 31, 2008

South Cottesloe Beach - Port Jackson sharks

I spotted four Port Jackson sharks (Heterodontus portusjacksoni) off South Cottesloe yesterday afternoon. They were resting on the sandy floor where the water was about 5 meters deep.

The next two photos are the more presentable ones that I took after many attempts to dive down and get near them. It would have been easier if there was a rock or something around them that I could hold on to.

Finally when I began to feel a slight cramp in my calf muscles, I decided to move on.

I have seen the fish before when I visited Aquarium Western Australia. But seeing them in the wild is definitely a special experience to me.

Monday, December 29, 2008

South Cottesloe Beach - Feather star

Feather star!
It was sitting quite happily next to another "star" until I turned over the rock and found it! I found them in a reef hole when it was low tide.

It has ten brownish or reddish arms. It wasn't very large - just a few centimeters across.
Ok. I have to admit I have no idea what species it is.

Soon after I started taking photos, the animal started moving.

Its agility was impressive. Waving its ten arms, it soon glided across the body of the sea star.

Pinnules are the side branches on the arms, which give the animal its feathery appearance. The animal uses the tube feet on the pinnules to trap plankton and suspended particles for food. Unlike sea stars, the mouth of a feather star is on the upper side of the body.

The cirri enable the animal to attach itself to some kind of support, like rock and sponge.

A close-up on the cirri

Penguin Island - Other invertebrates

The arrow points to the reef platform in the south of the island where I snorkeled and saw some gorgonians. Below are some other critters I saw there.

This gloomy octopus caught my eye almost immediately after I hit the water.

I saw a number of ctenophores (or comb jellies) in the water. I have seen them before at Cottesloe. So I didn't spend too much time on them.

While I was swimming around the reef overhangs where the gorgonians live, I spotted a huge colony of Zoanthus praelongus. This is the second time I saw this species. I first saw them at Cottesloe. This colony probably was three times as large as the one I saw at Cottesloe.

Later, while exploring the shallow seagrass bed, I saw these southern bailers (Melo miltonis). They were quite large, about 25 cm or so in length.

And on the way back to the shore, I came across this delicate sea anemone (Heteractis malu).
What's different about this one is that there was so much purple coloration on its short, stubby tentacles. Most of the other delicate sea anemones around it had just purple-tipped tentacles.

I found this sea star which I think is a Patiriella brevispina when snorkeling in the east side of the island.

The upper surface seems to be covered by some kind of plates with small spines (left). The sea star has orange tube feet (middle) and even an orange stomach (right)!

Sunday, December 28, 2008

Penguin Island - fan corals

Sea fans, fan corals or gorgonians (Mopsella klunzingeri?) are some of the most beautiful creatures that I have come across underwater.

I found them under overhangs when I was exploring the reef platform at the southern shore of the island. These animals don't rely much on the symbiotic algae in their tissues for food production. Thus they can live where it is not really well-lit in the sun. They rely on the strong currents to bring them food.

Taking their photos was really a challenge to me because of the waves. They were just a foot or two below the surface. I had to be careful and hold on to whatever I could so that the waves won't push me into the reef surface. (It must hurt!) But also, the light conditions were really not that good. It was one of those moments that I hoped I was diving instead, and could stay underwater as long as I want and find the best positions to take those photos. Anyway, despite the poor image quality, I don't blame my camera or its owner. They tried their best!

Gorginians have calcareous spicules in their tissues for support. However, they also have a kind of protein called gorgonin in their skeletons, hence their rigid but flexible branching structures.

These are surprises to me! I only knew that there were brittle stars in the gorgonian branches when I came home and looked at the photos in their actual size!

Well, yet another reason to return to the same spot with my camera again!

Friday, December 26, 2008

Penguin Island - fishes (2)

What a sight to behold!

I watched a huge school of banded toadfish (Torquigener pleurogramma) parading past me at Penguin Island.

Thursday, December 25, 2008

Penguin Island - fishes (1)

Some of the fishes I saw while snorkeling around the reef platform at the southern end of the Penguin Island three days ago:

A female Shaw's cowfish - Aracana aurita
This boxfish has three pairs of blunt spines on the body. One pair of the spines are over its eyes, which is possibly why it's called a cow-fish.

In a group, there are one dominant male fish, one dominant female and other females. When the male fish dies or disappears for whatever reasons, the dominant female will mourn by changing its sex and become a male! A male fish has blue and yellow stripes on its body.

Western butterfish - Pentapodus vitta

1. Blue-spotted goatfish (Upeneichthys vlamingii)
2. Zebra fish (Girella zebra)
3. Crested morwong (Cheilodactylus gibbosus)
4. Gobblegut - (Apogon rueppellii)

An interesting thing about gobbleguts is that the male incubates the eggs in its mouth until hatching!

Sunday, December 21, 2008

South Cottesloe Beach - Western smooth boxfish

The female western smooth boxfish (Anoplocapros amygdaloides) is one of my favorite underwater photography subject.

The boxfish is also known as a neutron bomb fish. The name comes from the fact that some of them can release an ostratoxin that's powerful enough to wipe out all living things within a confined space, like in a tank.

In the wild, the boxfish can swim away after releasing the toxin, so it won't get killed itself.