Dwarf sea hare at Woody Head

Thanks to Peter Scharf for the photo of this dwarf sea hare, Aplysia parvula, taken while he was snorkelling off the reef at Woody Head in early January 2017.

Sea hare, Aplysia parvula; photo by Peter Scharf

Dwarf  sea hare, Aplysia parvula; photo by Peter Scharf

The Sea Slug Forum gives information about this species, plus a photo of a juvenile with the shell visible. The mantle grows over the shell as the animal matures. These sea hares, vegetarians all, are small, up to 6 cm (just over 2 inches) in length.

Another goody at Woody!

Dancing the flamenco at Woody Head

We went to Woody Head on Saturday for the regular folk music/dance event that our friends have been doing for over 20 years, but only for the day. It’s a good spot for snorkelling and looking in rock pools (nudibranchs!), as many of my previous posts attest.

We weren’t there Sunday but Peter and Linda were in the water as usual, and Linda found a Spanish dancer (Hexabranchus sanguineus). I’ve longed to see one in the wild and managed to while snorkelling in the Lord Howe Island lagoon, but it was a long way down so I didn’t get a proper look. (All photos by Linda Scharf)

Hexabranchus sanguineus 15/5/2016 Woody Head NSW

Hexabranchus sanguineus 15/5/2016 Woody Head NSW

Hexabranchus sanguineus 15/5/2016 Woody Head NSW

Hexabranchus sanguineus 15/5/2016 Woody Head NSW

Hexabranchus sanguineus 15/5/2016 Woody Head NSW

Hexabranchus sanguineus 15/5/2016 Woody Head NSW

Hexabranchus sanguineus 15/5/2016 Woody Head NSW

Hexabranchus sanguineus 15/5/2016 Woody Head NSW

Hexabranchus sanguineus 15/5/2016 Woody Head NSW

Hexabranchus sanguineus 15/5/2016 Woody Head NSW

Hexabranchus sanguineus 15/5/2016 Woody Head NSW

Hexabranchus sanguineus 15/5/2016 Woody Head NSW

Wikipedia says:

During daytime, the Spanish dancer hides away from the light in the crevices of its natural habitat to only come out late at night. It feeds on various species of sponge. Like all nudibranchs, it is hermaphrodite and its bright red to pink egg ribbon has a spiral shape related to the size of the animal so relatively large. The latter is coveted by some other species of nudibranch as Favorinus tsuragunus or Favorinus japonicus. The Emperor shrimp, Periclimenes imperator, is a commensal shrimp that is commonly found living on Hexabranchus sanguineus.

Well done, Linda. Next time I’m staying overnight!

The lion kings

You’ll not hear these lions roar (Jane in Cape Town says lions don’t roar but merely cough, and she should know – Attenborough and Disney, you lied!), but they can certainly do you an injury if you mess with them.

The spines are venomous as distinct from poisonous, which is something different. The Smithsonian says:

Some people use the words interchangeably because once in the body, the chemicals do similar damage, attacking the heart, brain or other vital targets. But the terms do mean very different things. Traditionally, venomous creatures bite, sting or stab you to do their damage, while you have bite or touch poisonous critters to feel their effects. That means venomous organisms need a way in, like fangs or teeth.

In fact, lionfish are distinctly edible as long as you avoid the spines. Several countries have invasive populations creating environmental havoc in their seas, but have made an industry of catching and serving them in restaurants – a win-win situation in those places.

Those spines are defensive and can give you an extremely painful, but not fatal, prod.

NOAA says:

The lionfish’s sharp, slender spines are located on the dorsal, anal and pelvic fins. The venom is a combination of protein, a neuromuscular toxin, and a neurotransmitter called acetylcholine. The sting causes intense pain, redness and swelling around the wound site. Although the worst of the pain is over after an hour or two, some people report pain and tingling sensations around the wound for several days or weeks. On rare occasions, when the venom spreads to other parts of the body, people may experience headaches, chills, cramps, nausea, and even paralysis and seizures.

Now back to Woody Head, where Peter Scharf took these photos. The first three are of the zebra lionfish, Dendrochirus zebra. Its distribution in Australia is Shark Bay, WA to Sydney, NSW. (Distributions are given in a clockwise direction around the country.)

OLYMPUS DIGITAL CAMERA

Zebra lionfish, Dendrochirus zebra; photo Peter Scharf

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Naked (gills) at Woody Head

Peter has been busy with his underwater camera. He found some nudibranchs while snorkelling at Woody Head, northern NSW. Many thanks to Peter for letting me use his photos.

I’m sure you know already but, in case you don’t, the name  ‘nudibranch’ means ‘naked gill’. Nudis are (usually) tiny molluscs that are brightly coloured and apparently taste ghastly to potential predators (at least according to Ed Ricketts, who had a chew). They have been measured at 6 mm to 31 cm (0.25″ to 12″ for you imperialists).

National Geographic explains:

They are carnivores that slowly ply their range grazing on algae, sponges, anemones, corals, barnacles, and even other nudibranchs. To identify prey, they have two highly sensitive tentacles, called rhinophores, located on top of their heads. Nudibranchs derive their coloring from the food they eat, which helps in camouflage, and some even retain the foul-tasting poisons of their prey and secrete them as a defense against predators.

Nudibranchs are simultaneous hermaphrodites, and can mate with any other mature member of their species. Their lifespan varies widely, with some living less than a month, and others living up to one year. …

Some nudibranchs are solar-powered, storing algae in their outer tissues and living off the sugars produced by the algae’s photosynthesis.

The first is Hypselodoris maritima …

Hypselodoris maritima

Hypselodoris maritima

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The racing stripe flatworm

The Woody Head rock platform and bay have many great marine animals easily seen by snorkellers. I’ve written many posts about this area; you can use the search function on this blog to track them down.

An example is the beautiful marine flatworm, Pseudoceros sp. [Update: Gary Cobb of http://www.nudibranch.com.au/ thinks it is an undescribed species of Pseudoceros.]

Pseudoceros bifurcus

Pseudoceros sp.; all photos by Peter Scharf

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Cownosed rays at Woody Head

I haven’t been to Woody for a while, and I wish I’d seen the massed gathering of cownosed rays (Rhinoptera neglecta) there last weekend. There’s a media report and photos at ABC North Coast.

The Australian Museum says:

Cownose rays are usually found in large schools near the surface. They have a distinctive bi-lobed head, with two large fleshy lobes under the snout.

They apparently feed in these large groups, searching the sea bottom for crustaceans. The Woody Head bay is relatively shallow, and these came in really close to shore, as the photos show. Nice!

Sleeping underwater

On the weekend, perfect subtropical winter weather induced us to go to Woody Head for a snorkel – sparkling waters, fairly calm, water temperature greater than air temperature. Off the rock platform, there’s a spot that is sheltered by a curve of rocks, with a shallow wall (about 2 metres) covered with weed. Here you can find lots of subtropical small fish fluttering about, and nudibranchs if you’ve sharp eyes. It’s also a nursery for the larger fish (like the flathead fishermen love to catch) you can see in the bay.

In the bay you can also see small rays resting on the bottom. They zip off as you approach – a timely reminder that if you are walking in shallow water when the tide is out, you need to do the “stingray shuffle” so that you don’t put your foot down on one. Their barb is not venomous, but a stab would be painful (and no one wants to “do a Steve”, either).

The whole bay is a green sea turtle (Chelonia mydas) home, too. We saw four resting in the snorkelling area. All but one zoomed off when they saw us, and that one stayed still, snoozing in the weed. I only realised I was holding my breath while waiting for the turtle to come up and take one for itself when I felt myself wanting to breathe suddenly.

Green sea turtle; photo by Daniel Schwen, Wikimedia Commons

You can read about green sea turtles in Australia here.

I didn’t have the breath-holding problem with the next snoozers – probably because I know they don’t need to come up for air. Two spotted wobbegong sharks (Orectolobus maculatus) were parked under rock ledges where a current flowed over them, giving them all the oxygen they needed. They rest there during the day and come out to feed on fishes, crayfish, crabs and octopuses.

Spotted wobbegong; photo by Richard Ling, Wikimedia Commons

Heather is going to buy me that sticker that says “Remember to breathe!” I might need it.

A silver star for Christmas

Best Christmas present! This glaucus washed up by the heavy seas courtesy of the cyclone up north …

Glaucus atlanticus, a nudibranch, floats on the surface of the ocean, along with other members of the “blue brigade“. It can wriggle a bit, as this one was in its pond, but is mostly at the mercy of wind and currents, as are its confederates.

It feeds on the bluebottle, Physalia physalia, and moves the bluebottle’s stinging cells from its stomach into its own tips, so anything trying to eat it will get a mouthful of bluebottle stings. Other nudibranchs do this: see Evolution Happens for a description.

This one was about 3 cm long. The hole on the left side is a reproductive pore. Glaucus is a hermaphrodite.

I don’t see them very often, and this one was a special surprise on Christmas morning. Thanks, Mother Nature!