The beautiful Achilles Tang.

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Achilles Tang – Photograph by Brian Skerry, National Geographic
In other places around the world, coral has been decimated by bleaching and disease, but the southern Line Islands’ reefs retain their resilience.
Scientists believe the key to coral health is intact ecosystems, where all the native species—including planktivores such as the vividly marked Achilles tang seen here—play their part.
The Achilles tang is one of the most spectacular fish available for the aquarium, but it is also one of the most difficult to keep.
This fish swims continuously, and usually at a very high speed, so it requires a large tank with plenty of open space.
It also requires fairly turbulent water movement.
When kept in conditions of less-than-ideal water movement and/or in too small a tank, this fish will be very nervous, usually not feed, and wither and die fairly quickly.
It is usually fairly expensive, so this may help prevent hobbyists with less-than-ideal conditions from keeping this fish.
via Achilles Tang Picture — Line Islands Photo — National Geographic Photo of the Day.

The Alfred Manta Ray.

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The Alfred Manta, (Manta alfredi), one of the largest rays on the planet, is currently listed as vulnerable in eastern Australian waters with recorded individuals numbering in the few hundred.
Gary Cranitch’s awe-inspiring image is an important reminder that we still have much to do to ensure the survival of this beautiful species.
Photo: (Queensland Museum: Gary Cranitch)
Source: Spectacular science photos nominated for 2014 Eureka Prize – ABC News (Australian Broadcasting Corporation)

“The Red Handfish.”

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THIS IS ONE fish that will always be caught red-handed. Ok, bad pun, but it is an interesting fish.
Endemic to Tasmania’s eastern coast, the red handfish is so named because of its apparent use of its fins as hands, even using a type of walking motion on the seafloor.
It’s a benthic fish, preferring to hang around the sandy and rocky bottoms of the seafloor. They’ve been observed eating small crustaceans and worms.
There are two colour varieties – one with red embellishments (seen in the image above) and the other a right red all over. It grows from about 6cm to about 13.5cm long.
The red handfish was first discovered in the 1800s around Port Arthur.
In the 1980s a small population was found on the Actaeon Islands, south of Hobart, and the biggest population to date was found on a reef off Primrose Sands around Hobart (10 individuals) in the 1990s.
However, in a survey in 2005, no handfish were found in those areas.
They may be hanging on, because in 2010, three individuals were found in the Primrose Sands location.
Though the species hasn’t had a full, systematic survey of its numbers, it seems that populations are few and far between, and there’s likely to be not more than 1000 individuals in the wild, and likely only hundreds.
The red handfish was known as the Brachionichthys politus, but in 2009, it was re-categorised as Thymichthys politus.
Threats to red handfish include poaching for use as pets. Its low reproductive rate and low dispersal rate make is a challenge for the species’ survival. Fragmentation of the populations is also a challenge for reproductive success.
via Red handfish Thymichthys politus – Australian Geographic.

Devil Rays Dive Deep.

image1.jpg__800x600_q85_cropBy Rachel Nuwer

Divers exploring warm waters around the world often encounter Chilean devil rays, gentle marine creatures that can grow up to ten feet long.

Scientists have just discovered that the rays harbor an impressive secret, however: they regularly undertake epic dives more than a mile deep.

These remarkable dives came as a surprise to researchers who reported the finding today in Nature Communications. In retrospect, they note, the rays’ physiology did hint at this ability.

Chilean devil rays possess a special organ called the retia mirabilia, which is also found in deep-diving species such as great white sharks. In those animals, the veined structure fills with warm blood that exchanges heat between vessel walls. This helps to keep the marine creatures’ brain warm when they descend to freezing depths. But Chilean devil rays, researchers assumed, spent all of their time at the surface. Why would they need such a structure?

To solve the puzzle, an international team of marine biologists attached satellite tags to 15 Chilean devil rays captured off the northwest coast of Africa, near the Azores archipelago. The team monitored the rays’ movements for nine months and found that the animals were tremendously active. They sometimes traversed up to 30 miles of ocean per day, with each covering a distance of up to 2,300 miles over the nine-month period. Even more impressive, however, was the rays’ diving abilities. They regularly dove below 1,000 feet, with a maximum-recorded depth of 6,062 feet. This means that Chilean devil rays undertake some of the deepest dives ever recorded for marine animals, the team reports.

The journeys into the deep seem to be no sweat for the animals. One individual, for example, dove nearly 4,600 feet six days in a row, and overall, the rays spent more than five percent of their time in deep water.

The deep dives explain the presence of the previously enigmatic retia mirabilia, the team writes. At the depths recorded by the trackers, rays would encounter temperatures as chilly as 37˚F, so the extra flush of warm blood provided by that organ likely makes those dives possible. Additionally, the researchers found that the rays spend more time basking near the water’s warm surface both one hour before and one hour after a deep dive, implying that the animals are preparing for and recovering from encounters with the cold.

The rays aren’t undertaking these dives just for fun, of course. Based on the animals’ movement patterns—oftentimes a quick bee-line descent followed by a slower step-wise ascent—the researchers think they are probably foraging on fish or squid that live well below the surface.

The unexpected findings, the authors write, demonstrate “how little we know” about Chilean devil rays and the role they play in ocean ecosystems. Given that these animals were recently listed as endangered (largely due to a growing demand for their gills by practitioners of traditional Chinese medicine), “this ignorance has significant conservation implications,” the team continues. As with any species, the more we know about them, the better equipped we will be for protecting them—and for knowing what we stand to lose should they disappear.

via Chilean Devil Rays Found to Be Among the Deepest-Diving Animals in the Ocean | Science | Smithsonian.

“Largetooth Sawfish.”

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ONE OF THE world’s largest fishes, this strangely wonderful shark-like ray occurs in waters around the world. Individuals can grow larger than 6.5m (including the saw) and weigh up to 600kg.
They are named for their distinctive saw-like snout with about 14-23 protruding teeth (which are actually scales) on each side. They use the snout to find and stun prey, which includes schooling fish such as mullet, as well as molluscs and crustaceans.
Unlike many fish that either live in freshwater or marine environments, the sawfish can move through both (known as being ‘euryhaline’). Juveniles are often found in freshwater, whereas adults are most often in estuary or marine waters.
What were formerly considered separate species, P. pristis, P. microdon, and P. perotteti, are now listed under the one species P. pristis and thought to be subpopulations occurring in tropical waters in the Eastern Atlantic, Western Atlantic, Eastern Pacific and Indo-West Pacific oceans.
Our local sawfish (Indo-West Pacific population) population is one of the last strong ones, listed just as Vulnerable nationally; therefore, they are important to the whole species’ survival globally.
They are found in the muddy bottoms of Australia’s big northern rivers and estuaries, including the Fitzroy and Ord rivers in WA, the Adelaide and Daly rivers in the NT, and the Mitchell and Leichhardt rivers in Qld. They have been found 400km from the sea.
Sawfish are ‘ovoviviparous’, meaning that a mother incubates her eggs inside her until they are ready to be born. A litter ranges from 1-11 pups and individuals don’t reach maturity until about 8-10 years. The Australian population has been estimated to live for up to 35 years.
Threats to sawfish extinction
The shark-fin trade is a major threat to their survival globally, as is the traditional medicine trade. Their unusual saw-like snout is also a treasured item, which makes them a target for illegal trade.
Their snouts also cause them to easily become trapped in nets, so this type of fishing is also a threat.
A recovery plan for the species listed as Vulnerable in Australia is currently being developed.
via Largetooth sawfish pristis pristis – Australian Geographic.

The Mandarinfish, Beautiful but Poisonous.

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The mandarinfish is one of only two known species that produces a blue pigment. (Credit: Jim Trodel/Flickr)
by Becky Crew
One of the most beautiful fish in the ocean, but the mandarinfish (Synchiropus splendidus) has got so much more going on for it than all those pretty colours.
At home in the sheltered lagoons and inshore reefs of the Pacific Ocean, ranging from the Ryukyu Islands off the coast of Japan, to warm Australian waters, this little dragonet is covered in tiny spines to inject a toxic mucus into anyone who tries to handle and/or eat it.
The mandarinfish contains two types of secretary cells in its colourful epidermis – one that produces a thick mucus coating to protect it from the elements, and another that produces a toxin to protect it from predators.
And not only is this toxic mucus coating dangerous, particularly if it makes it into a predator’s open wound, but reportedly, it smells disgusting.
“Every scientist and book [who] talks about the mandarinfish makes mention of its strong, unpleasant smell,” says Esther Inglis-Arkell at io9. “
That stink is not incidental. The mandarinfish needs the smell, and the spines, because it lacks one of the most basic protective measures in the marine world: It doesn’t have scales.”
There’s nothing like thick mucus and an unpleasant stench to turn someone off their potential meal.
Read on further via Beware of the beautiful but poisonous Mandarinfish – Australian Geographic.