Tuesday, September 23, 2008

Sea hare oozing purple goo

While I was wondering on the South Beach of Fremantle last Saturday, I found two sea hares (Aplysia species) that had been washed ashore. And both were still alive.

I saw this one first. It was about 10-12 cm in length I think.

This one was near the water's edge. Similar to the first one in size. It seemed weak and was nudged further and further towards the shore by the incoming tide. Anyway, after a while, I didn't see it on the shore anymore. So I would assume it made it back into the ocean.

I have seen sea hares a few times and put up a few posts about them before. They are amazing animals, both when they are doing their beautiful dances and when they are copulating. But when they are washed ashore and dying, they are sad to look at.

The first sea hare was pretty stressed I guess. I saw it oozing some purple ink near its "tail" (?) after a while. Yes, it was purple, as I read here.

The purple ink is used for defense, but it is also excreted when the animal is disturbed (it seems).

A group of scientists paired a sea hare and a lobster in the same aquarium and found that the sea hare could use its purple ink to confuse the predator. Some compounds in the ink appear to have an effect on the lobster's nervous system. And while the lobster was still "assuming" that it had caught the sea hare or was still trying to figure out what's happening, the sea hare would run for its life. There are three short clips of their experiments here.

Monday, September 22, 2008

The blue bottle's tentacles

I have read about the coiled tentacles of the blue bottle but never quite seen them. The tentacles of those blue bottles I found on the shore were often very much decayed and looked like they have all "melted" into a blue mass.

Yesterday at South Cottesloe, I saw some blue bottles which have landed in pools of water on the rocky shore. I have taken a few shots of their tentacles. Yes, now I believe they have coiled tentacles :)

Sunday, September 21, 2008

The Blue Layer - Sea lizard

Wow! What a surprise. I went beachcombing today at South Cottesloe (my favorite beach) and found a sea lizard washed ashore. The sea lizard is part of "the Blue Layer" (MESA's webpage). Now I have met four (dead/dying) members of the Blue Layer.

This is how it looked like when I found it. I read that it lives its life upside down, like a violet snail does. And I suspect the blue round thingies are its eggs.

I turned it and took another shot. (The animal was about 5 cm in length)

The thing (or one of the things) about the sea lizard that I find amazing is that it can eat up the blue bottle's tentacles and use the stings as its own!

Compound ascidians on South Beach, Fremantle (2)

The cloudy skies, wet weather, plus strong winds means that I can't go snorkeling today. So I decided to write another post about my beachcombing finds on the South Beach of Fremantle. (My last post about these creatures which I found on South Beach is here.)

I still don't know anything about their scientific names but their beautiful colors and patterns lured me into taking shots of them!

This one is about 20 -25 cm across.

This one is just around 5 cm across.

This one must look really nice in a super-macro photo. Unfortunately, because of the film of water covering the creature, I couldn't get an in-focus close-up shot. (I should have brought some tissues with me - No, I won't use my shirt.)

Well, those are the photos of compound ascidians - each animal being a living, colored (colorful?) "neighborhood" with hundreds of residents living really really close together.

Well, this one is a solitary ascidian, unlike the ones shown above.
In these photos, you can see the two siphons that the animal uses to take in and expel water. This sea squirt is about 10 cm across. There are pieces of broken shells stuck on it too.

I realized quite early in my blogging days that it's impossible to learn everything under the skies.
And blogging shouldn't turn into a chore.

So, I sometimes just post about animals without even trying to find out what species they are. Some of these animals that I try not to worry much about include the different species of sea stars, wrasses, corals, seaweeds, and sea squirts - species that are often not easily identified because of the great extent of variations even in the same species. I suppose for now it is sufficient to just know that they exist, and that to a limited extent, I've made simple observations of them.

The blue layer - Blue bottle, By-the-wind sailor, Violet shell

I went to the South Beach of Fremantle this morning hoping to snorkel. But the water conditions were poor, so I beachcombed instead.

I found many blue bottles (a.k.a. Portuguese Man O' War, Physalia species) and violet shells (Janthina janthina) on the shore. They must have been blown to shore during the recent storm. And I saw a by-the-wind sailor (Velella velella) too, for the first time.

These animals are part of "the Blue Layer", which is basically a huge group of floating animals that drift across the ocean, and that they are camouflaged by having dark blue colors on the upper body surfaces (so the sea birds won't see them easily) and whitish colors on the underside (so that the fishes won't see them easily).

By-the-wind sailor (Velella velella)
This animal is similar to the Porpita (Blue button), which is also a "member" of the Blue Layer. Unlike Porpita, Velella has a sail and has shorter tentacles at the margin of the blue disc. Nevertheless, both species occur as a colony, not as a single animal.

Blue bottle (Physalia species)
Like Porpita and Velella, the blue bottle is also a colony of organisms. They have trailing tentacles that can sting and paralyze small fishes. They have a single coiled tentacle that can be meters in length. They are said to be capable of delivering painful stings even when they have been washed ashore.

Now, the violet shell (Janthina species) - which unlike the last two species - is a single organism. And it is actually a predator of Velella and Physalia! This animal is always born as a male and would later change into a female. It makes the bubble raft by secreting some kind of mucus (waterproof, of course) that can be used to trap air and keep the animal afloat.

The MESA website has an explanation about the Blue Layer.

Wednesday, September 10, 2008

Coral Bay experience (7) - Other fishes II

This is my third post (and I guess should be my last post) about the fishes I saw in Coral Bay.

White-spotted eagle ray (Aetobatus narinari)
This species is said to move around in large schools but I saw only one. An interesting fact about it is that it can reach about 800 cm in length, including tail. So I suppose a large portion of that is the length of its tail. I always wonder why they need such a long tail.

Female spotted boxfish (Ostracion meleagris)

Convict surgeonfish (Acanthurus triostegus)
Algal grazers on the reef. They get their name from the sharp spines on both sides of the tail base. Many websites say that the spines can be as sharp as scalpel blades!

Surf parrotfish (Scarus rivulatus)
Colorful residents on the reef. Parrotfishes play a role in bottom sediment formation in a reef system by ingesting coral rock, grinding them to powder and passing it out with their feces. Anyway, one interesting fact that I just learned is that they sleep in a cocoon-like mucus envelope that they make. And the envelope is supposed to mask their scent, protecting them from predators like the moral eel.

Sunday, September 7, 2008

Crabs with lost limbs

I went back to the South Cottesloe beach again today when the tide was low. I explored the part of the rocky shore that was usually inundated and simply can't be accessed easily.

As I was taking photos of the crabs, I noticed that more than half of the crabs that I saw have lost at least one of their limbs. That's interesting.

Crab 1: Lost one limb on the left side of the body
(It was upside down when I spotted it.)

Crab 2: Lost one limb on the left side and two on the right side!

Crab 3: Lost one limb on the right side.

Crab 4: Lost half of the limbs it had! And for your information, it was still moving and alive - though I wonder how much longer it could stay that way.

I have seen crabs so many times on the beach but only started to notice the ones with lost limbs at Coral Bay. I first noticed that some crabs were so slow to flee and so easy to photograph - soon I realised that those were the ones which have lost one or more of their limbs. The next few photos were taken at Coral Bay.

Crab 5: Only one limb on the left side was missing.

Crab 6: The big claw was gone.

Crab 7: Also the big claw was missing.

Well, next time, when you see a crab on the beach, check if their limbs are all intact. And if they have lost a limb or two, it probably won't be too long before they regenerate new ones. Some websites and this one say that it is common for crabs to self-amputate their limbs to get away from predators and the lost limbs can be regenerated!

Wow! How ignorant of me - I always thought that only sea stars and lizards can do that. Obviously both crabs and lobsters can regenerate a limb too.

By the way, even though they were physically impaired, they still looked beautiful.