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.

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.

Harpa harpa – beautiful predator snail

Harpa harpa

The family Harpidae comprises elegant marine gastropods with shell, resembling the strings of a harp. They are nocturnal hunters, hiding in the sand during the day and feeding on crabs and shrimps at night. The prey is enveloped by the foot and mucus, then saliva containing digestive enzymes is injected. Finally, partly digested crab is sucked out by the mollusc.

Amazing mimicry: Pseudoceros imitatus

Pseudoceros imitatus (Mimic Flatworm), one of my favourite flatworms, mimic Phyllidiella pustulosa (Pimpled Phyllidiella), very common toxic nudibranch. Phyllidiella can emit very toxic substances on the skin, extracting them from the sponges it feeds on. Our flatworm unfairly enjoys poisonous fame, avoided by predators!

Pseudoceros imitatus (Flatworm!)

Can you tell flatworm from nudibranch on this photo?

Do you see the difference?