Issue # 38: Hidden treasures

DIVE’s Summer ’25 magazine is here! Packed as always with brilliant photography and great writing – subscribe quickly so you don’t miss out on a copy!

Subscribe for just £1 to get your copy!

A DIVE INTO THE UNKNOWN

Raja Ampat is one of the world’s most sought-after diving destinations but it’s far from being completely explored. Award-winning photographer Jenny Stock dives into the unknown as she visits some previously undiscovered spots on board the Raja Ampat Aggressor, accompanied by some of her fantastic photography of never-before-seen reefs.

SAVING MEXICO’S MANTAS

The Caribbean Coast of Mexico is home to one of the world’s largest aggregations of whale sharks – and a gathering of giant manta rays follows them. Mark ‘Crowley’ Russell talks to Karen ‘Manza’ Fuentes about her determination to make sure their populations are preserved, and why they may well be the long-awaited third species.

OCEAN PHYSICS

Helen Czerski began studying the science of bubbles at the Scripps Institution of Oceanography when she realised she needed to learn to scuba dive – and fell in love with it. She talks to Jo Caird about combining her passion for the underwater world with a background in physics in her award-winning science book Blue Machine: How the Ocean Shapes Our World.

MULTI-DISCIPLINE DIVING

Some underwater photographers prefer macro over wide-angle; others big fish or landscapes. Each takes time to learn and perfect, but diving under the Cement Plant Pier in Barbados provides photographers with a single site to practice them all. Award-winning photographer Catherine Holmes gives us her top tips for study and some stunning results of her own.

UNDERWATER EARNINGS

Lots of people love taking pictures underwater, and there are some super-talented amateurs out there. Most people will only ever see their pictures shared among social media friends – but can you earn an income from sharing them with the world? Colin Marshall shares tips from his 30-year history as a stock agency photographer.

SPEAKING OF PHOTOGRAPHERS…

While there some talented amateurs out there among the underwater photo pros, many, many divers pick up a camera and turn into nightmares with bubbles. Mark ‘Crowley’ Russell shares some of his experiences from his time a full-time dive professional, and what steps divers need to take before ever even thinking about taking snapshots!

BIG SHOT TOGETHERNESS

DIVE’s latest Big Shot underwater photography competition called for images of underwater animals living together – in harmony or, as the case might be, not. Check out the best of the entries from our Big Shot Living Together photo competition as they were meant to be seen – on the pages of a glossy print magazine.

More DIVE Magazine previews:

• DIVE Magazine Spring 2025 – Ocean Colour Scenes
• DIVE Magazine Winter 2024/25 – Never Stop Learning
• DIVE Magazine Autumn 2024 – a giant stride for mankind
• DIVE Magazine Summer 2024 – exploring the depths
• DIVE Magazine Spring 2024 – the Magazine with Bite

*£1 for 3 months print and digital subscription (normally priced at £23.99 in the UK) including all content and 100+ digital back issues. Renews at regular yearly subscription price after 3 months – no obligation; cancellable any time. Available worldwide (international shipping extra).

Click here to take out a regular yearly subscription

The post DIVE Magazine Summer 2025 preview appeared first on DIVE Magazine.

Issue # 37: Ocean colour scenes

DIVE’s Spring ’25 magazine is here! Packed as always with brilliant photography and great writing – and you don’t want to miss our in-depth feature on liveaboard safety

Subscribe for just £1 to get your copy!

RISE OF THE MACHINES

Artificial Intelligence – AI – is one of the hottest topics in the world today. Some believe it is the future of human civilisation; others that it’s little more than a glorified search engine. One place it’s making waves, however, is in image creation. Award-winning photographer Jenny Stock takes a look at whether it’s a force for good or evil in the world of underwater photography.

Read: Artificial Intelligence in underwater photography – a force for good, or evil?

THAILAND AGGRESSOR

The Similan Islands are regarded as some of the best dive spots on the planet – Mark B Hatter takes a trip on board Aggressor Adventures’ Thailand Aggressor to take a look at what all the fuss is about and discovers how spectacularly photogenic the reefs really are.

UNDERWATER ARTIST

Multi-award-winning photographer Catherine Holmes takes a very painterly approach to her underwater photography, using the same focus on light and colour as her art with brush and canvas. She took some time out of her busy schedule to talk to DIVE about the method behind the creation of her underwater masterpieces.

Read: Painting with light – an interview with Catherine Holmes

LIVEABOARD SAFETY

Liveaboard safety has been very much in the news over the last two years, culminating in the tragic loss of 11 lives when Sea Story sank in November 2024. Mark ‘Crowley’ Russell takes a look at how we, as divers, can help to ensure our safety on board, since it’s quite clear some operators aren’t especially interested.

Read: Liveaboard safety – how divers can change it and when to walk away

ULTIMATE DIVE SITES

Where are the best dive sites in the world? Expedition guide and underwater photographer Todd Thimios’ new book Ultimate Dive Sites presents the author’s definitive account of those he loves the most, and we feature three less well-known spots in this fascinating series of extracts.

Read: Searching for the best – an extract from Todd Thimios’ Ultimate Dive Sites

BUDGET OR LUXURY?

Raja Ampat is home to possibly the best diving in the world – but it comes at a price. Writer and Photographer Todd Aki takes a look at a budget homestay option and compares it to the comforts of a luxury resort.

Read: Luxury resort versus budget homestay in Raja Ampat

BIG SHOT PORTRAIT GALLERY

DIVE’s latest Big Shot underwater photography competition called for Portraits – images that engage both the reader and the subject. We had some fantastic entries and the winners are here, in all their glory, printed on the shiny art-quality stock of our beautiful magazine. Check them out here and look out for the details of our next competition, ‘Living Together’.

Read: DIVE’s Big Shot Portraits – THE WINNERS!

More DIVE Magazine previews:

• DIVE Magazine Winter 2024/25 – Never Stop Learning
• DIVE Magazine Autumn 2024 – a giant stride for mankind
• DIVE Magazine Summer 2024 – exploring the depths
• DIVE Magazine Spring 2024 – the Magazine with Bite
• DIVE Magazine Winter 2023/24 – Expect the Unexpected

*£1 for 3 months print and digital subscription (normally priced at £23.99 in the UK) including all content and 100+ digital back issues. Renews at regular yearly subscription price after 3 months – no obligation; cancellable any time. Available worldwide (international shipping extra).

Click here to take out a regular yearly subscription

The post DIVE Magazine Spring 2025 preview appeared first on DIVE Magazine.

Former instructor Mark ‘Crowley’ Russell on why continuing education programmes are essential for both divers and dive businesses.

By Mark 'Crowley' Russell

I’ve been asked many times what is the best thing you can do to become a better diver – to which I reply: ‘Never stop learning.’

I think it applies to almost everything in life, but scuba diving, in which we must learn to exist in an environment completely alien to our own, is an activity where it is especially relevant.

While the laws of physics remain immutable, we are affected by them differently underwater. We become lighter and then heavier with every breath we take, we are unable to move as quickly as we can at the surface, and we cannot fight even the most gentle movement of water in the same way our feeble bodies cannot withstand hurricane force winds.

Regardless of which club or agency a diver chooses to start their newfound pastime with, the entry-level course will only ever confer on them the basics of dealing with that new approach to everyday physics.

Most divers will go on to complete an Advanced Open Water equivalent (or Open Water Plus, as I think it should be called), the entry-level adjunct which permits divers to descend to 30m. However, once that permission has been granted, many call an end to their scuba-diving education.

Most divers will be aware of the many continuing education programmes available. There is a wide range of speciality courses covering everything from boat diving and drift diving, to nitrox diving, night diving, search and recovery and underwater photography, plus a host of marine science and conservation-type programmes.

With the exception of an enriched-air certification to use recreational nitrox, most dive operators do not require that recreational divers take extra courses to undertake certain activities.

Beyond needing an AOW equivalent to take part in 30m dives, I know of no dive centre in my own experience that requires divers to have a drift-diving certification to go drift diving, or a night-diving certification to dive in the dark.

Some of the speciality programmes, therefore, come in for a bit of stick. Certain divers scorn what they consider to be fairly basic courses such as boat diving or drift diving, and yet most of these programmes, however simple they may appear, contain a lot of valuable information from which even experienced divers may learn.

Consider that many divers in land-locked areas will have little or no experience with boats, and PADI’s often-mocked ‘Boat Diver Specialty’ teaches much more than just how to fall off a RIB and get back onto it.

Drift diving – while exhilarating – can be terrifying for the inexperienced diver, so to have some managed practice under the guidance of a dive professional is an important step on many divers’ educational ladder.

Others – such as PADI’s Search & Recovery Specialty – go well beyond the scope of the average diver; ‘Underwater Naturalist’ borders on university-level marine biology; and underwater photography classes will transform the results of camera-wielding amateurs.

Basic dive skills are inevitably improved as a consequence of exposure to new information and learning new underwater techniques.

Yes, continuing education is a money-spinner for dive centres. Margins in the scuba-diving industry world can be vanishingly small, but continuing education courses tend to be a little more lucrative than entry-level programmes.

Dive professionals are therefore encouraged to up-sell such courses – it generates income and helps to create trust and loyalty between businesses, brands and customers.

Am I promoting the sale of such courses? I absolutely am. Not specifically for any particular brand (I tend to default to PADI as I am a former PADI instructor), but for the benefit of everyone involved – on both sides of the payment window.

A better understanding of the underwater world enhances both dive enjoyment and diver safety, but progress requires training, and training requires that viable businesses exist to provide it.

Do I need a ‘Master’ Scuba Diver certification?

Once a diver has completed some extra speciality programmes, added a stress and rescue diver course with emergency first-aid training, and logged 50 dives, some agencies – PADI, SSI and SDI among them – will reward divers with a ‘Master Scuba Diver’ or ‘Master Diver’ certification, confirmation that they have joined the scuba diving ‘elite’.

Such certifications are widely criticised as an unnecessary gimmick (probably because PADI charges divers £30-odd for the privilege of being issued a new card), and there are, sadly, many divers who sneer at the concept of a scuba diver with 50 dives somehow being at the pinnacle of their recreational diving careers.

There is, therein, a valid point – 50 dives does not an expert diver make, but, equally, it represents a significant investment of time and money into a scuba-diving education – perhaps five years or more for somebody who only gets to take a single-week dive holiday each year – and a commitment to scuba diving that is as strong as those who can afford to dive more regularly.

Such a person is somebody I would warmly welcome into a dive centre in the days when I was working as a full-time dive professional. Not because I thought they might spend more money on courses (one can always hope!), but because they are clearly somebody who is interested in learning more about the activity they have chosen to pursue.

They, therefore, enjoy diving more, are more enjoyable to dive with, and are – very importantly – safer divers.

Not all clubs and agencies offer an MSD equivalent, but some form of recognition after passing educational milestones is a worthy goal. I personally do not think there should be any charge for the extra certification (especially since the arrival of digital certification cards), but I think the level of achievement is something to be encouraged and should be, in my opinion, a bare minimum prerequisite for professional level training.

Continuing education is the lifeblood of the recreational scuba industry – and a pathway to the world of technical diving or careers in underwater photography, marine biology, or even search and rescue diving, for those prepared to take the first step.

People will undoubtedly continue to turn up their noses at the ‘Master Scuba Diver’ concept but, in all honesty, I’d rather dive with someone who waved that level of certification at me than somebody who didn’t think it necessary to continue their underwater education beyond 30 metres

More great reads from our Magazine

• The Young Dive Ambassadors of Atlantis Dumaguete
• Ocean Life – Alan J Powderham’s Coral Triangle Cameos
• Inspiring Hope – an interview with Cristina ‘Mitty’ Mittermeier
• Ross Merrin on training as a BDMLR Marine Mammal Medic
• Shark and Jolanda Reef – Howard Rosenstein on the day it all began…

The post How to become a better diver: never stop learning appeared first on DIVE Magazine.

Approaching its 25th anniversary, The UK’s National Lobster Hatchery in Padstow continues to develop its successful stock-enhancement programme.

Words and photographs by Lewis Jefferies

The UK’s National Lobster Hatchery (NLH) rears the next generations of Cornish lobsters through their early stages, giving this commercially exploited species a far greater chance of survival in the wild, while also helping support the livelihoods of local fishers.

For divers in the UK, a lobster is always an exciting find. One of the more charismatic critters on the reef, they will often be seen peering out of crevices and overhangs and may come out to investigate and even defend their patch.

They are also frequently seen inside creel fishing pots, which can be crammed full of them.

The European lobster (Homarus gammarus) is the UK’s most valuable commercial marine species, with many coastal communities relying upon it to make their living.

To help support the sustainability of the wild population, the NLH in Padstow was opened in 2000. Rearing the hatchlings through their early stages can increase their chances of survival by up to 1,000 times.

The NHL is led by researchers and scientists who collaborate with fishers, local restaurants and the community to help maintain a sustainable fishery. The demand for lobster is rising, and other lobster populations in Scandinavia and the Mediterranean have collapsed due to overfishing.

Lobsters in the UK are classified as vulnerable to local overexploitation, and the work of the NLH complements fisheries management measures to help ensure the UK’s population is kept sustainable.

ON THE LOBSTER MATERNITY WARD

Chris Weston, a technician at the hatchery, holds out a ‘berried hen’ or egg-bearing female, to show me the eggs around her pleopods (feathery parts underneath the abdomen), while members of the public peer through the window from the visitor centre.

‘We receive female lobsters from local fishermen,’ Chris explains. ‘They will call us when they land one with eggs that are nearly ready to hatch, and one of the team members will go and collect them.’

A single female can carry anywhere from 2,000 to 45,000 eggs, depending upon her size. However, only about one in 5,000 of these are expected to survive when laid in the wild.

The lobster gestation is between nine and 12 months, with the water temperature having an affect on when the eggs will hatch – the colder the water, the longer the gestation will be.

To control their volume of larvae, the hatchery keeps females stored at different temperatures in separate tanks, which allows them to bring the eggs on when they are ready to care for them. The hatchery has a ‘maternity ward’ where the mother lobsters are kept.

‘When the hen is ready, she will do a headstand to release the eggs,’ Chris says. ‘They then naturally float to the surface, and in the wild, this usually happens at night for safety, so predators can’t see the larvae.’

In the hatchery the tiny lobsters are collected in the morning after they have hatched and transferred to the larval system to begin their first moult.

In the first two to four weeks, baby lobsters are classed as planktonic – meaning they float around suspended in the water column – which makes them extremely vulnerable to predation. To increase survival rates, the NLH rears the larvae until they are around three months old.

Like all crustaceans, they grow through moulting, where they shed their shells and take on water to increase in size. The hatchery rears juveniles through their first four stages, where they are kept floating in recirculating aquaculture systems, which mimic conditions in the wild. Salinity, water quality and pH balance are checked daily.

Once they reach their last larval stage – looking like perfect miniature lobsters – at around two inches long, they are then transferred to a system of trays to separate individuals and prevent cannibalism.

‘Each set of trays can carry around 4,000 animals, and we have a capacity of over 24,000 in total,’ says Chris. When their last planktonic moult is complete, they can be released to the ocean, as they possess the natural instincts they need to burrow and shelter on the seabed.

ANCIENT SCRAPPERS

Lobsters date to the Jurassic period when they shared the planet with dinosaurs. The European lobster has an unmistakable appearance – dark-blue armour with yellow, white, and red markings, large powerful claws and long red antennae.

They are either left- or right-clawed, and usually, one side is larger and used for crushing prey, while the opposing one is usually lighter and used for slicing.

Male lobsters love to fight and will seek out other males when competing for a mate. It is not unusual for them to lose one of their claws during battle, but this isn’t a problem for long, as they can regrow them.

They are believed to live up to 100 years in the wild, and the largest European lobster ever landed was in Fowey, Cornwall, in 1931. It weighed a staggering 9.3kg and measured 127cm (50 inches) in length. Its crushing claw alone weighed 1.2kg.

The lobster mating process is a complex one, in which the female must shed her shell before mating. This leaves her very vulnerable, and the couple may stay together for a few days. Once ready they will rear up, press their bellies together and topple over, with the female on top, which is when the male deposits his sperm package.

The female will then move off independently and gorge herself on food while her shell hardens. They are caring mothers, and, once the eggs have developed, they will continuously fan fresh water over their eggs to provide a fresh stream of oxygen until they hatch.

PROTECTING LOBSTERS AT SEA

A number of local fishers around Cornwall are licensed to land egg-bearing females when one is found in a creel. When an individual is landed with eggs in advanced gestation, the fishers contact the hatchery which sends a technician to collect mother and eggs. Earlier in gestation they are returned to the sea.

The fishing community has developed its own conservation system and marks egg-bearing females with a V notch cut into their tails, restricting them from being sold until the notch grows out.

It is illegal to land and sell a berried hen in the UK, but some fishers have been known to scrape off the eggs and sell the mature females. Studies have established that cutting the notch does not introduce disease nor increase the mortality of lobsters. It has been illegal to land a V-notched lobster in Britain since 2000.

Fishers will also use a special gauge to ensure that lobsters are big enough to land. They measure the length of the carapace or shell from the back of one eye socket to the edge of the carapace, which has to be 90mm or more before the lobster can be landed. This is a standard set by the Inshore Fisheries and Conservation Authority (IFCA).

Back at the hatchery, once the tiny lobsters have grown out of their planktonic stage they are released around Cornwall and the Isles of Scilly. Hatchery staff will take hundreds of lobsters to different locations and release them into rockpools at low tide.

These are often organised as public events, where all ages can take part in the release. This helps to enthuse people about the marine environment, and also inspires the next generation of ocean conservationists. Others are released from boats.

Fishers and lobster hatchery staff release larger numbers from a boat, using a specialist lobster ‘floom’, where a hose is extended to the seafloor and the lobsters are poured in through a large funnel. Divers also take between 400 and 600 individuals and release them on a suitable reef during a dive.

In the summer of 2023, a dive release was organised at the National Maritime Museum in Falmouth, outside its public underwater viewing screen. Members of the public were able to watch marine conservation in action.

Dive and boat releases are a preferred method, as it is believed that the lobsters have a greater chance of survival, being in deeper water and able to quickly find a home on the reef. They will then stay in an area for around two years until they reach sexual maturity at which point they will set off to find a mate.

DNA CHECKS

Scientists from the University of Exeter are working with the hatchery and have developed a method of identifying lobsters through their DNA. Two DNA samples, from each egg-bearing female over the past decade, have been taken to gather DNA from the mother, father and larvae. One from the pleopods and one from the eggs, that are then preserved in a freezer.

Dr Carly Daniels, head of research for the hatchery, says: ‘We have been taking samples for over ten years now, so have an amazing resource that, once we are in a position to analyse, may give us vital evidence to show the effectiveness of our work.’

With the DNA identification database in place, the NLH is currently looking for further funding to help analyse its samples which will allow it to identify hatchery-reared animals after release.

‘We have a lot of anecdotal evidence from fishermen in areas where we have done releases with the NLH,’ says Dr Daniels. ‘The fishermen have reported many more lobsters of the size you would expect in release areas, given the length of time for the lobsters to grow since we started releasing, and they are not seeing such an increase in numbers in other areas.’

Although this observation is a good indicator that the programme is working, using this DNA identification technique would provide solid evidence of its success.

As well as working with the local fishing community to source egg-bearing females, the team at the NLH have also partnered with local restaurants, wholesalers and retailers on a fundraising scheme named ‘Buy One Set One Free’, where customers purchasing a lobster can opt to donate a small amount of money to the hatchery.

This allows customers to support the release of baby lobsters into the sea by way of a small donation that funds the hatchery’s conservation work. When you visit a seafood restaurant, look out for the sign, and if buying a lobster be sure to support the programme.

The work of The National Lobster Hatchery continues to grow and become more successful every year. In 2017 it opened another hatchery in Newlyn Harbour and has plans to extend to more satellite hatcheries and partner with more organisations to continue its conservation and research projects and raise awareness of sustainability in our oceans.

The hatchery’s work has a huge impact on sustaining the local lobster population in Cornwall and supporting the livelihoods of people who depend on it, while also making a huge contribution to public engagement and awareness of the marine environment.

More great reads from our Magazine

• The Young Dive Ambassadors of Atlantis Dumaguete
• Ocean Life – Alan J Powderham’s Coral Triangle Cameos
• Inspiring Hope – an interview with Cristina ‘Mitty’ Mittermeier
• Ross Merrin on training as a BDMLR Marine Mammal Medic
• Shark and Jolanda Reef – Howard Rosenstein on the day it all began…

Click here for a full subscription or single issue

The post The National Lobster Hatchery – giving lobsters a helping hand appeared first on DIVE Magazine.

The Coral Triangle in the western Pacific Ocean is home to the greatest variety of marine life on the planet. In his latest book Coral Triangle Cameos, Alan J Powderham, with scientific consultant Sancia van der Meij, focuses on the ‘small majority’ – the diminutive yet vital and often overlooked inhabitants of this amazing world.

In the 12 fascinating chapters of Coral Triangle Cameos, Powderham and van der Meij look at everything from the smallest crustaceans hiding on the reef to the weird and wonderful life forms drifting in the open ocean on blackwater dives.

With Alan’s stunning photographs and extremely informative text, you are taken on a journey into a complex, interdependent marine world brimming with life.

In this extract from the amazing book we take a look at a selection of chapters and the beautiful images that accompany them.

MUSHROOM CLUB

The Fungiidae family – known as mushroom corals – are predominantly solitary single-polyp corals which may have multiple mouths. As with other Cnidaria, their tentacles are armed with stinging cells, called nematocysts.

As hexacorals, they form limestone structures to house their polyps. Their arms form a radial symmetry of six, though this geometry is not readily obvious. By comparison, the arrangement of the eight-tentacled polyps of octocorals is generally
quite plain to see.

Individual polyps of mushroom corals reach impressively large sizes, with some solitary species exceeding more than
25cm. While the juveniles start life anchored to the substrate by a stalk, most species are free-living as adults. I have occasionally seen them collect in large aggregations, a mobility which is quite at odds with our normal conception of corals’ sedentary lifestyle.

They are also able to right themselves if turned upside down, for example by wave action. However, beyond all the biology, a prime attraction is their wonderful abstract patterns and intricate structures.

CRYPTOBENTHIC CHARMERS

Cryptobenthic, which basically means ‘hidden on the bottom’, refers to the tiny, secretive fish which typically hide within the coral crevices and reef debris. Consequently, they are easily overlooked but are now considered to be key contributors to the viability of the reefs.

Recent research has focused on discovering the apparently huge deficit in the nutrients required to sustain the complex ecosystems of coral reefs.

The larvae of cryptobenthic fish are not broadcast but settle locally, thus creating a bounteous cycle of nutrition concentrated within the confines of the reef.

Blennies are prominent citizens of this community and are widely represented in tropical and temperate seas, with an estimated 350 species. They provide a variety of charming characters as they peer out from their hideaways with large, appealing eyes.

This description is qualified, since a sprinkling of the notorious fangblennies number among this family. Most blennies are herbivores but the fangblenny is the exception.

It operates in borrowed clothes, as it mimics cleaner fish. This enables it to approach and take a bite out of unsuspecting patrons attending cleaning stations.

SMART SQUID

Among invertebrates, cephalopods are widely admired for their intelligence. They match some of the smartest vertebrates, which is pretty impressive for a mollusc.

Yet, being molluscs, they have evolved along completely distinct pathways. Their brains are cited as prime examples of convergent evolution. A direct experience of this mental prowess was provided early in my introduction to diving in the Coral Triangle.

My interest, then, was predictably attracted by the more obviously impressive subjects such as dense shoals of large fish. Underwater, good photography generally demands close proximity to the subject – a familiarity not readily welcomed
by the creatures of the reef.

So I was delighted, when encountering a large shoal of barracuda, to find that my local dive guide was well versed in the correct procedure. He immediately signalled to me to avoid further approach, and wait while he circled deeper to take position on the far side of the shoal. From this manoeuvre he was able to shepherd the fish towards me.

So, it came as quite a surprise when he blankly refused to apply the same tactics when we happened upon a school of squid. ‘Squid, like cats – too smart – don’t herd like barracuda’ was his amusingly laconic but insightful explanation.

DECORATED DECEPTION

Decapod means ‘ten footed’. Such anatomy is clearly evident in the crab pictures below, despite their liberal decoration of stinging hydroids.

This living array of potent protection is also a transferable asset. Remarkably, a moulting crab will painstakingly transplant
its collection of hydroids to the new carapace. It is a delicate and precarious operation. It has to be undertaken during the period of heightened vulnerability while the crab’s new exoskeleton hardens.

The spider crab has also adopted a singular approach to decoration, specialising in corallimorpharians, which most
notably disguise the crab’s outline.

Decorator crabs have a covering of fibrous material armed with tiny hooks known as setae. These enable them to attach their adornments like Velcro.

ALIEN DRIFTERS

While the rich biodiversity of the Coral Triangle may readily overwhelm the senses, some bizarre transparent creatures may float by unnoticed.

As illustrated, these range from ctenophores to heteropods and even pelagic ascidians. Ascidians are typically sessile creatures and establish colonies that can spread extensively.

The brief phase of the ascidian tadpole is totally focused on settling, affording it no time to feed. Accordingly, they have no mouth but do possess a range of chordate components including a primitive spine, and rudimentary eyes and brain.

After settlement, these redundant body parts are all absorbed in a transformation that matches the terrestrial example of the caterpillar to butterfly metamorphosis. But for the ascidian, it is a case of losing rather than gaining mobility.

The larva, now attached to the substrate, transmutes into a vase-like form for which it promptly develops intake and exit siphons to continue life as a filter feeder.

Not all ascidians sacrifice mobility, as there are pelagic species known as pyrosomes which may be seen rolling over the substrate like aquatic tumbleweed.

Ctenophores are voracious predators and come in a range of shapes and body sizes. Like a tiny iridescent refugee from Star Trek, with its gut full of plankton, this comb jelly has clearly enjoyed a successful nocturnal hunt.

Heteropods, (first image below) known curiously as sea elephants though actually molluscs, virtually defy description.

More great reads from our Magazine

• Inspiring Hope – an interview with Cristina ‘Mitty’ Mittermeier
• Ross Merrin on training as a BDMLR Marine Mammal Medic
• Shark and Jolanda Reef – Howard Rosenstein on the day it all began…
• ‘Toxic Trumps’ – venomous sea creatures and how to treat their stings
• Are work-for-training scuba diving internships worth it?

Click here for a full subscription or single issue

The post Alan J Powderham’s Coral Triangle Cameos appeared first on DIVE Magazine.