Marine Life & Conservation
Construction Crews – who digs those holes in the sand?
Gliders, Mantis Shrimps and Gorgeous Prawns… Mouth filled with sand, the Pennant Glider emerged from his hole and expelled the sand onto the growing pile at the edge of the hole. His partner darted into the hole and emerged with another mouthful of sand that he too spat onto the pile. Their burrow was formed in a crevice in the sandy rubble bottom and they had simply taken up residence in it and kept it clear. But the varying currents kept filling it, shells rolled into it, and they maintained it by suction and jet expulsion. This simple method of clearing a hole is used by many fish species as a sort of undersea vacuum cleaning system.
Not all such undersea residences are natural however. Some of the most impressive burrows on the reef are made by the Mantis Shrimp. They have immensely powerful front claws, and some species are able to break a camera lens with a blow. They can easily dig out a substantial hole in the sand on the reef, and Mantis shrimp are largely responsible for the more impressive holes on the reef.
The Giant Mantis creates a fully lined, superbly constructed burrow for himself in soft sand. These holes seem to be lined with a cement made with spittle and bits of sea-grass, and they are extremely strongly built.
Smaller holes become the home of Commensual Partnerships between a prawn and a goby.
The Goby can see and hunt but can’t dig, and the prawn can dig but is blind and can’t hunt. So they team up, and form a mutually beneficial relationship.
The goby’s task is to find food, and the prawn shares his bounty. The goby acts as the attack alarm, and is incredibly sensitive to movement and light. Few people know to wait and watch their interaction but it can be hilarious.
The prawn’s job is to dig and shovel the debris out of their home as it accumulates, depositing it in the right place by following the spine of the Goby with a feeler. The goby moves to point in the direction where the prawn must shovel the next pile of sand. This works very well until an extra goby arrives, or another shrimp joins the team.
We watched for half an hour as a pair of industrious shrimp both shovelled sand, small coral pieces and bits of shell out of the hole under the direction of a rather harassed-looking goby. The problem came when they both shoved at the same long coral piece, and it got stuck in the mouth of the hole. Looking baffled, his line of retreat closed, the goby darted off and hid under a rock. The two prawns shoved vigorously until the mouth of the hole ruptured, and a full day’s work dropped back into the hole. The goby came home, and you almost hear him muttering with rage as he haughtily dived through the debris to seek sanctuary below.
Where there are two gobies and only one shrimp sharing a hole, it is even funnier, as the two gobies point the prawn in opposite directions. We watched a completely paranoid prawn shoving a pile of sand and shells out of the hole as directed by the first goby and then pushing the same pile of sand back into the hole by following the spine of the second goby. The hole never changed, and we left before the prawn gave up.
Look out for holes in quiet corners on rubble or sandy bottoms, duck behind a rock, and watch. It’s worth it.
Words: Jill Holloway
Pics: David Holloway
Copyright: Ocean Spirit
Marine Life & Conservation
Leading UK-based shark conservation charity, the Shark Trust, is delighted to announce tour operator Diverse Travel as a Corporate Patron
Corporate Patrons provide a valuable boost to the work of The Shark Trust. The Trust team works globally to safeguard the future of sharks, and their close cousins, the skates and rays, engaging with a global network of scientists, policymakers, conservation professionals, businesses and supporters to further shark conservation.
Specialist tour operator Diverse Travel has operated since 2014 and is committed to offering its guests high quality, sustainable scuba diving holidays worldwide. Working together with the Shark Trust will enable both organisations to widen engagement and encourage divers and snorkellers to actively get involved in shark conservation.
“Sharks are truly at the heart of every diver and at Diverse Travel, we absolutely share that passion. There is nothing like seeing a shark in the wild – it’s a moment that stays with you forever!” says Holly Bredin, Sales & Marketing Manager, Diverse Travel.
“We’re delighted to celebrate our 10th year of business by becoming a Corporate Patron of the Shark Trust. This is an exciting partnership for Diverse and our guests. We will be donating on behalf of every person who books a holiday with us to contribute towards their vital shark conservation initiatives around the world. We will also be working together with the Trust to inspire divers, snorkellers and other travellers to take an active role – at home and abroad – in citizen science projects and other activities.”
Paul Cox, CEO of The Shark Trust, said:
“It’s an exciting partnership and we’re thrilled to be working with Diverse Travel to enable more divers and travellers to get involved with sharks and shark conservation. Sharks face considerable conservation challenges but, through collaboration and collective action, we can secure a brighter future for sharks and their ocean home. This new partnership takes us one more valuable step towards that goal.”
For more information about the Shark Trust visit their website here.
For more about Diverse Travel click here.
Marine Life & Conservation
Shark Trust Asks Divers to help with Shark Sightings this Global Citizen Science Month
Whether you are stuck for ideas of what to do with the kids or are off on the dive trip of your dreams. You can get involved in Citizen Science Month and help the Shark Trust by providing vital data about sharks are rays both close to home and further afield.
In addition to reporting the sharks and rays you see on your dives, the eggcases you find on the beach, the Shark Trust is looking for some specific data from divers who are asked to report any Oceanic Whitetip and Basking Sharks.
Oceanic Whitetip Sharks
The Shark Trust are looking specifically for Oceanic Whitetip Shark sightings over the coming weeks and months. So, if you are diving anywhere in the world, please report your sightings via the website or app.
Website: https://recording.sharktrust.org/
App: Search The Shark Trust in your app store
The Oceanic Whitetip. Known for their incredibly long dorsal and pectoral fins, this species was once the most abundant oceanic-pelagic species of shark on the planet.
Large and stocky, they are grey or brown above, and white below and famous for their huge rounded first dorsal fin and paddle-like pectoral fins. The fins also highly prized within the shark fin trade. Whilst they are mostly solitary, Oceanic Whitetips do occasionally hunt in groups.
An inquisitive species, they were easy prey for fisheries. Combined with their low reproductive rate, they were inevitably at high risk of population depletion. And declines of up to 99% have been reported in certain sea areas. They are listed as Critically Endangered on the IUCN Redlist (2019).
Conservation efforts to discourage further declines include listing on CITES Appendix II and CMS Appendix I. They’re also the only species prohibited from take by all the Tuna RFMOs (Regional Fisheries Management Organisations). However, these measures do not mean that Oceanic Whitetips are not still caught – whether targeted or as bycatch – in some parts of the world. With populations declining at such a high rate, effective implementation of management measures is essential to ensure that the species can recover.
If you are lucky enough to get an image of an Oceanic Whitetip and you record your sighting on the Shark Trust app or website YOU CAN WIN! All images submitted with sightings, that also give consent to use in conservation messaging, will be in with a chance to win an Oceanic Whitetip T-shirt and mug. The competition will run until the end of “Shark Month” in July – so keep those sightings (and images) coming in.
Basking Sharks
Basking Shark (Cetorhinus maximus) season is upon us, and the Shark Trust is asking everyone to keep an eye out for these majestic giants over the summer months. If you see any, you can record your sighting to the Basking Shark Sightings database.
Each year, these mighty fish return to British waters to feed on plankton. You may see one, (or a few if you’re really lucky) from around April-October. They can be seen feeding at the surface of the water, where they look like they’re basking in the sun. Thus, their name!
Sighting hotspots around the British Isles include southwest England, Isle of Man, north coast of Ireland, and western Scotland. The Sea of the Hebrides is the most prolific sightings area in Scotland, but they have been spotted all around the coast and have even ventured into some of the sea lochs. The Shark Trust has received thousands of sightings since the Basking Shark project began, but more data is needed to truly understand what is going on with population numbers and distribution. You can help by recording your sightings this summer.
Great Eggcase Hunt
The Shark Trust has an Easter Egg Hunt with a difference for you to try. Take part in the Great Eggcase Hunt and get involved with a big citizen science project that helps shark, ray and skate conservation. And it’s an enjoyable activity for all the family.
The Shark Trust also want snorkellers and divers to record their underwater eggcase findings. Underwater records help pinpoint exactly where sharks and skates are laying their eggs and can help link to beach records. Learning the depth and substrate that they lay on also helps better understand the species.
Find out more: https://www.sharktrust.org/great-eggcase-hunt
Whether you are diving, snorkelling or exploring on the beach you can take part in Citizen Science Month and get actively involved in shark and ray conservation. Find out more: www.sharktrust.org
-
News3 months agoHone your underwater photography skills with Alphamarine Photography at Red Sea Diving Safari in March
-
News2 months agoCapturing Critters in Lembeh Underwater Photography Workshop 2024: Event Roundup
-
Marine Life & Conservation Blogs2 months agoCreature Feature: Swell Sharks
-
Blogs2 months agoMurex Resorts: Passport to Paradise!
-
Blogs2 months agoDiver Discovering Whale Skeletons Beneath Ice Judged World’s Best Underwater Photograph
-
Gear News3 months agoBare X-Mission Drysuit: Ideal for Both Technical and Recreational Divers
-
Gear Reviews2 months agoGear Review: Oceanic+ Dive Housing for iPhone
-
Marine Life & Conservation2 months agoSave the Manatee Club launches brand new webcams at Silver Springs State Park, Florida