Octocorals

The title of this week’s DKHQ Marine Fact sounds like a sci-fi animal; the visual being half coral, half octopus. Although not a sci-fi creature, this animal is a coral.

When I use the word coral in conversation it often elicits responses such as, “Oh, you mean the coral in the Great Barrier Reef?” Yes, the Great Barrier Reef does have a diversity of beautiful corals, but you don’t have to travel to the tropics to see corals. The corals I am discussing today are found in the cooler temperate waters of Southern Australia. You may need to put on a thicker wetsuit to view them, but they are just as beautiful and colourful as their tropical cousins.

Here are some incredibly interesting facts about octocorals:

Fact 1: The ‘octo’ in octocoral represents the eight feathery tentacles found on each polyp that form the coral. The feathery tentacles are attached to the stomach.

Octocorals are beautifully colourful.
Octocorals are beautifully colourful.

Fact 2: Octocorals are filter feeders, meaning they eat microscopic organisms floating in the water column. The feathery tentacles, as described above, act like fingers swaying in the water current, capturing organisms such as plankton (microscopic animals) and phytoplankton (microscopic algae). Each tentacle is hollow, allowing the organisms to travel from the feathery tips down to the stomach.

Fact 3: Octocorals form colonies that are attached to the seabed or other hard structures such as large rocks.

Fact 4: To see octocorals you will need to SCUBA as they prefer to live at depths between 4-50m.

Fact 5: Octocorals are in the scientific Order Alcyonacea and consist of soft corals, gorgonians and sea whips.

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What the devil……?

Every venture into our amazing marine world provides me with an opportunity to learn something new and to interact one-on-one with some wonderful creatures.

During one dive in Port Phillip Bay, located in Victoria, Australia, the Southern Blue Devil’s iridescent blue colours immediately caught my eye.  Scientifically known as Paraplesiops meleagris, this beautiful fish is endemic to southern Australia. The Southern Blue Devil can only be found in the beautiful waters between Perth in Western Australia to Port Phillip Bay in Victoria to a depth of up to 45m.

The Southern Blue Devil loves to live under ledges and in crevices and caves. They are fiercely protective of their territory, especially during breeding season. My first encounter with the Southern Blue Devil was during breeding season. The male of this species can be a little aggressive if you get too close to their territory, especially if you have any blue colours on your SCUBA kit or wetsuit. My SCUBA mask at the time was made of clear perspex and rubber lined with bright blue rims around the eyes. Thinking I was a competitor for it’s territory, this male Southern Blue Devil told my SCUBA mask in no uncertain terms that it wasn’t welcome.

Southern Blue Devil 1: Dalton Koss HQ SCUBA mask 0.

The Southern Blue Devil on the defensive mode due to my blue rimmed SCUBA mask coming across as a potential competitor.
The Southern Blue Devil on the defensive due to my blue rimmed SCUBA mask appearing to be a potential competitor.

Although quite a visually funny story, here are some other interesting facts about the Southern Blue Devil.

Fact 1. Similar to human finger prints, adult Southern Blue Devils can be individually identified and monitored due to their unique pattern of markings on the lower part of their gill cover.

Fact 2: Adult pairs will stay together during the breeding season, protecting their eggs that are usually laid on rock surfaces in narrow crevices.

Fact 3: The Southern Blue Devil is protected by law across Australia as they are endemic, that is, they are not found anywhere else in the world.

Fact 4: Known to be curious, the Southern Blue Devil will usually interact with SCUBA divers even during non-breeding season.

Fact 5: The Southern Blue Devil loves to eat small crustaceans, snails, worms and sometimes other small fishes.

If you ever have an opportunity to SCUBA across Australia’s southern oceans, look out for the Southern Blue Devil. In fact, it will probably find you first.

The Southern Blue Devil loves living in and around crevices, ledges and caves.
The Southern Blue Devil loves living in and around crevices, ledges and caves.

Slugs in the nud’

At Dalton Koss HQ we come up with some creative names to describe some of the more interesting creatures that can be found in our marine front yards.

Slugs in the nud’  are nudibranchs. Nudi what? Nudibranchs.

Nudibranchs are oceanic snails, do not possess a shell and are mostly brightly coloured.

To break it down, Nudi = nude and branchs = gills. As these snails do not have shells for protection, their gills are nude and exposed (see image below).

Without a shell covering, the nudibranch's gills can be found on the top part of its body and exposed to the water.
Without a shell covering, the nudibranch’s gills can be found on the top part of its body and exposed to the water.

Nudibranch Facts

1. The bright colours of nudibranchs are used as defence mechanisms to avoid predators.

2. Many are able to camouflage with their surrounding environment, such as corals and sponges.

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3. Nudibranchs do not make a tasty meal. In fact, they are toxic and poisonous to eat. This is because nudibranchs feed on the stinging cells of sea jellies, anemones and corals.

4. Nudibranchs can be found at different depths in both warm and cool ocean waters.

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Although not in the same size category of many other sea creatures, they do create a level of excitement for DKHQ when spotted under water.

Seahorses & Seadragons

Amongst Dalton Koss HQ’s favourite animals and plants are the enigmatic seahorses and seadragons.

Are they real? Do they really exist?”, DKHQ is often asked.

 Yes, they are real and live in both tropical and cooler oceans across the globe.

Regarded by most as resembling half horse half fish, these gentle oceanic creatures spend their time slowly cruising amongst seagrass meadows, seaweed gardens and coral looking for small shrimp to eat.

Both seahorses and seadragons belong to the bony fish family, Syngnathidae, which also includes pipefish and pipehorses (a DKHQ marine fact for another day) .

Seahorses tend to have an upright vertical position while stationary or moving,  while seadragons tend to have a horizontal stationary and moving position. Although seahorses and seadragons look different, they are closely related.

There are some AMAZING facts about seahorses and seadragons.

FACT 1: The seahorse and the seadragon are the only animals in the world where the male gives birth to the babies. Yes, you read correctly! The only animals in the world where the male gives birth. Female seahorses deposit their eggs into the male seahorse pouch where they are then fertilised. The male seahorse will carry the growing babies in the pouch until they are born, which is why some male seahorses look like they have a very big belly. This reproduction approach is very similar for seadragons, however,  the male seadragon will carry the babies in pouches that are attached to their tail rather than in their belly.

FACT 2: Seadragons can only be found in the cooler waters across southern Australia and no where else in the world. The Weedy seadragon is Victoria’s marine state emblem, while the Leafy seadragon is South Australia’s marine state emblem.

FACT 3: If you have an opportunity to dive amongst the tropical reefs of South East Asia, keep your eye out for the pygmy seahorse. No bigger than an average sized thumb, pygmy seahorses will only live on specific types of coral.

A pygmy seahorse attached to coral in the beautiful reefs of Malaysia. Image by Dr Elizabeth Strain.
Spot the pygmy seahorse attached to coral located in the beautiful reefs of Malaysia. Image by Dr Elizabeth Strain.

The next time you are snorkelling or diving amongst seaweed gardens, seagrass meadows or coral reefs, keep your eyes open for a beautiful seahorse or seadragon.

Sea Anemones of the Southern Ocean

At DKHQ we are constantly asked whether some of the facts portrayed on Finding Nemo are true, specifically the much difficult to pronounce Sea Anemone. Pixar did a wonderful job raising the profile of tropical reefs, although to the detriment of Clown Fish who, if the facts are correct, were being flushed down toilets by young children wanting to release ‘Nemo’ back into the ocean.

This aside, the often asked sea anemone questions at DKHQ are: a. can sea anemones sting, and b. can their poison kill humans? The answer to a. is yes and to b. is no. This public fascination with sea anemones inspired today’s DKHQ Marine Fact, with a focus on southern sea anemones.

Unlike the large sea anemones of our tropical reefs systems found across the globe’s equator line, the sea anemones of the southern ocean are comparatively smaller but just as beautiful and colourful. Here are some interesting facts:

1. Southern sea anemones always occur as solitary individuals usually in intertidal and subtidal areas.

2. All sea anemones have one opening, function both as its mouth and anus (this fact usually elicits some funny facial and noise reactions). Sea anemones are carnivores, on other animals.

3. The sea anemone body is supported by water pressure, which means when not in water their body and tentacles become floppy.

4. The tentacles of all sea anemones radiate from the mouth in one or many rows and are hollow. These tentacles contain stinging cells known in marine science as nematocysts. Each nematocyst contains a pressurised coil that can be pushed out to capture prey or used as self defence. The sea anemone use the nematocysts to stun, and in some cases, kill the prey.

5. Nearly all southern ocean sea anemones grow attached to a rock or some other type of hard structure. The exception to this rule (and when it comes to Mother Nature, there is usually one exception to the rule) is the Swimming anemone known by its scientific name as Phlyctenactis tubercles. (See image below). The Swimming anemone can move through the current or crawl along hard structures.

The Swimming anemone, Phlyctenactis tuberculosa.
The Swimming anemone, Phlyctenactis tuberculosa.

So why can’t sea anemones sting us? Our skin is too thick to be penetrated by its stinging cells, unlike many sea creatures with very thin skin. In the case of Clown fish, they have adapted over a long time for their skin to not be affected by the stinging cells and use the sea anemone as a place of protection from enemies.

DKHQ hopes you enjoyed these sea anemone facts and will leave you to enjoy the beautiful colours of some of the southern ocean’s sea anemones.

This beautiful sea anemone is known as Phlyctenanthus australis and can be found along Australia's intertidal shoreline that is exposed to ocean waves.
This beautiful sea anemone is known as Phlyctenanthus australis and can be found along Australia’s intertidal shoreline that is exposed to ocean waves.
This gorgeous red sea anemone is known as the Waratah Anemone and it's scientific name Actinia tenebrosa. This lovely Waratah Anemone can be found along the intertidal shoreline, often looking like a red blob at low tide.
This gorgeous red sea anemone is known as the Waratah Anemone and it’s scientific name Actinia tenebrosa. This lovely Waratah Anemone can be found along the intertidal shoreline, often looking like a red blob at low tide.
This fun orange and white stripped sea anemone is known as Anthothoe alboctinia and can be found under rocks or underhangs along Australia's intertidal shoreline that is exposed to ocean waves.
This fun orange and white stripped sea anemone is known as Anthothoe alboctinia and can be found under rocks or underhangs along Australia’s southern intertidal shoreline that is exposed to ocean waves. There are two variations to this sea anemone, white and orange stripes and brown and green stripes.