Some animals can chop off their own heads!

DID YOU KNOW that Elysia marginata is capable of decapitating itself when its body becomes infected with parasites?

Sounds fantastic, but it’s true!

What’s even more bizarre, the head gets around fine without its body. In three weeks, it regenerates a new body, perfectly functioning and parasite-free.

Elysia marginata

“We’ve known for a long time that sea slugs have regenerative capabilities, but this really goes beyond what we had thought,” said Terry Gosliner, senior curator of invertebrate zoology at the California Academy of Science.

To “puff up” is dangerous for pufferfish: myth or not?

Pufferfish will “puff up” as a defense mechanism if they are threatened. A shape that is more than double its original size, round and sometimes covered in spines is much more difficult to bite and isn’t very appetizing to a predator. 

However, just as people should stretch before exercising to avoid injuring themselves, puffers need to stretch out their muscles as well. Inflating yourself full of water so that your skin is stretched tight can be very painful, especially if your muscles aren’t used to it. Even though they sometimes do it just to stretch, puffing up often can be stressful for a puffer. So, it’s best if they do it only when they need to. 

Cyclichthys orbicularis.

Divers! Please avoid frightening puffers deliberately! It sometimes could be dangerous for them.

5 facts you didn’t know about pygmy seahorses.

Hippocampus bargibanti

All seahorses, including pygmies, are part of the family Syngnathidae. Ever since they were first discovered in 1969, pygmy seahorses have become stars of the reef and attract hordes of underwater photographers. 

So what do we know about pygmy seahorses?

  1. Pygmies range in size from 1.4 – 2.7cm, from the snout to the tip of the tail. Human finger nail to toe nail in size.
  2. Like other seahorses, it’s the male pygmy that becomes pregnant. He gives birth to around a dozen young after a gestation of 10-14 days.
  3. They feed on tiny crustaceans that share their local habitat.
  4. Pygmy seahorses differ morphologically from all other seahorses, possessing a single rather than paired gill openings in addition to a brood pouch located on the trunk, rather than the tail.
  5. They don’t have eyelids and are sensitive to light (photographers please note!).
Hippocampus waleananus

Want to know more about Pygmy Sea Horses and other fishes of Indo-Pacific region? Check photoguide Reef Fishes of the Coral Triangle by A.Ryanskiy.

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5 facts you didn’t know about Sea hares

Sea hare is any marine gastropod of the family Aplysiidae (subclass Opisthobranchia, phylum Mollusca).Sea hare is characterized by a shell reduced to a flat plate, prominent tentacles (resembling rabbit ears), and a smooth or warty body.

Petalifera ramosa
  1. Sea hares eat large seaweeds. Their color is diet-derived from the pigments of the algae.

2. This amazing invertebrate grows up to 16 inches in length!

3. All are simultaneous hermaphrodites with fully functional male and female reproductive organs. 

4. As they commonly occur in quite crowded numbers during the mating season, it often leads to chains of three or more sea hares mating together. 

5. To protect themselves they release a noxious ink that irritates the would-be predator and stops them in their tracks, in much the same way a skunk protects itself.

Aplysia parvula

More about Sea Hares you can find in the photoguide Nudibranchs of the Coral Triangle by A.Ryanskiy & Y.Ivanov.

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5 facts you didn’t know about frogfishes.

Latin name of the family is Antennariidae. There are about 47 known species of frogfish worldwide. Fascinating to divers and deadly for its prey, the frogfish is the ocean’s master of aggressive mimicry.

  1. Many of them can change color over time to camouflage within their surroundings. Unlike the chameleon, they are unable to change its color quickly. The process usually takes several weeks.
  2. Striated, or hairy, frogfishes usually mimic algae or soft corals, but can also mimic venomous black urchins.
  3. Their attack is amongst the fastest in the world, being able to trap prey in 0.006 seconds!
  4. The frogfish lacks a swim bladder. This structure is found in most swimming fishes; it maintains their buoyancy in a similar manner to a diver’s BC.
  5. Juvenile painted frogfish mimic toxic nudibranchs. Because of this behavior, they have little to fear from their own predators while being ignored by their prey, allowing easy ambush.

Unknown facts about well-known scallops

Iridescent Scallop Pedum spondyloideum @Jeanette Johnson

Every diver saw these scallops a lot of times. Some of us even tried to photograph them, fascinated by the row of unusual eyes between the tentacles. Less known it the fact that they help coral host to survive Crown of Thorns predation. Contact by starfish usually caused the scallops to generate repeated powerful jets of water, forcing starfish to move away. Scientists from the University of Queensland (L. M. DeVantier, R. Endean)

“Impact of the jets usually caused starfish to retract the sensory tube feet at the tips of the affected arm, raise the arm, and in most instances move away. However, in several interactions, starfish persisted in moving onto or over the scallop following initiation of the jets. On 2 occasions, this resulted in the starfish being lifted several cm above the coral surface by the continuing jets.”

As you probably already guessed, this clam is also a great subject for photography. More interesting facts and inspiring photos await you in the new book, available as paperback and Ebook.

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Night Dive Secrets: strange transparent fishes

Night dive in the tropical Indo-Pacific – it is always a possibility to find something new and strange. If you dived a lot after sunset you probably noticed strange transparent fishes slowly moving near the soft bottom.

Often the have a row of round dark spots running along the midline

They are hard to notice due to the transparent body and cryptic behaviour and not easy to identify to species. But I can suggest a family name: they are juvenile Lizardfishes, Synodontidae. Look again at the eyes and jaws and you’d recognise them!

Meet Hippocampus nalu, new Pygmy Seahorse from South Africa

Extremely cryptic and always cute, Pygmy Seahorses are very popular among scuba divers and underwater photographers. First of them, Hippocampus bargibanti was described in 1970 and until 2003 remained alone, later accompanied by Hippocampus denise & Hippocampus colemani (2003) Hippocampus pontohi  (2008) Hippocampus satomiae & Hippocampus waleananus (2009), all from Western Pacific. Hippocampus japapigu was described from Japan (2018). Finally, 2 days ago (May 19) Hippocampus nalu was described from Sodwana Bay, South Africa. For me, this is the day of victory for underwater photographers and citizen science.

Hippocampus nalu.  Photo: Dr Richard Smith

The Sodwana pygmy seahorse was described by Drs. Louw Claassens and Richard Smith. But it was actually discovered three years before, when a local dive guide Savannah Olivier found and photographed this tiny creature. Dr Louw Claassens and Dr Dave Harasti arrived in Sodwana in 2018 looking for an entirely different animals. We can just imagine how shocked they were after dive guide demonstrated a photo of local pygmy seahorse! Definitely undescribed one, found 8000 miles away from other members of the group!

If you photographed pygmy seahorses you know it is far from easy! Sodwana Bay reefs are exposed to waves action and conditions for underwater macro photography are challenging. Congratulations to scientists and Savannah Nalu Olivier, Instructor and Dive Master, Pisces Diving, Sodwana. Great job!

Pygmy Sea Horses: more information and photos: Reef Fishes of the Coral Triangle

Crown of Thorns: the frightening beauty

Acanthaster planci (Crown of Thorns) juvenile, 1.5 cm.

First of all about the beauty: Crown of Thorns juveniles are really handsome in their own spiky-snowflake way. They develop spines and begin to feed on coral only about one year of age, drifting as planktonic larval before that age. Getting bigger and bigger they are gaining more and more brutality and spike length.

Acanthaster planci (Crown of Thorns) juvenile, 5 cm. with commensal shrimp

Adult Crown of Thorns can grow up to a huge size – more than metre in diameter! A few interesting facts:

– Crown of Thorns are a natural part of the coral reef ecosystem. An increase in their numbers only occurs when the reef is unhealthy.

– In healthy reefs Crown of Thorns are playing a positive role by eating some of the faster-growing corals and giving the slower-growing corals a chance.

Acanthaster planci (Crown of Thorns) young adult

– Adult Crown of Thorns can survive without feeding for up to nine months. The normal lifespan of a Crown of Thorns is about four or so years.

Acanthaster planci adult
Acanthaster planci feeding on branching corals

Lacy scorpionfish

Lacy scorpionfish, Rhinopias aphanes holds top position on the bucket list of many underwater photographers. You can not find this fish visiting regular diving destinations like Anilao or Lembeh, you’d add some adventure (and money) and visit Papua New Guinea, Australia or New Caledonia.

Usually they are found on offshore reefs, not deep, sitting motionlessly in ambush near crinoid, perfectly matching with surrounds. You are lucky if you managed to get a small collection of differently coloured Lacy – Golden, Grey, Greenish, Red.