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Construction Crews – who digs those holes in the sand?

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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

www.osdiving.com

Jill Holloway lives in Mauritius and at Sodwana Bay Isimangaliso Wetland Park in South Africa. A PADI qualified Nitrox diver with over 1,500 dives, she is a passionate observer and preserver of the marine environment, and has a database of over 35,000 fish pics and hundreds of Gopro videos on fish behaviour, which she shares with her readers.

Competitions

WIN one of the NEW Momentum M20 Dive Watches!!!

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For this week’s competition, we’ve teamed up with our good friends at Nautilus Diving to give away one of Momentum’s new M20 Dive Watches as a prize!

Leading watch brand Momentum has introduced the new M20 series of watches. The new collection includes the M20 DSS Diver with a classic black dial, or striking Bahama yellow dial, and the M20 GMT Diver in a black & blue “Batman” version.

The M20 Dive watch features a solid 316L stainless steel case that is beautifully rounded and polished, taking its design cues from our original 1990’s Aquamatic model. The case is just under 42mm in diameter, but the smooth curves make it feel much smaller. Style, performance and unmatched comfort on the wrist.

The M20’s elegant yet durable design allows it to be worn in almost any situation. It has a 200M depth rating along with an off-set screw-down crown for added comfort.

The M20’s are also very legible, with its double-dome sapphire crystal with anti-reflective coating there is virtually no glare. At night, the SuperLuminova luminous dial and hands come to life, a vital feature for serious divers where light may not reach certain depths.

To be in with a chance of winning this awesome prize, all you have to do is answer the following question:

In a recent post on Scubaverse.com (which you can find here), we reported that the Women Divers Hall of Fame have announced the selection of how many new members who will constitute the Class of 2021?

Is it:

  • A) five
  • B) six
  • C) seven

Answer, A, B or C to the question above:

Nautilus Diving Momentum M20 Dive Watch October 2020

Competition
  • Enter the country you live in
  • Terms and Conditions: This competition is open to all visitors to www.scubaverse.com except for members of the Scubaverse team and their families, or employees of Nautilus Diving and their families. A valid answer to the competition’s question must be entered. If no valid answer to the competition’s question is entered, your entry will be invalid. Only one competition entry per entrant permitted (multiple entries will lead to disqualification). Only one prize per winner. All prizes are non-transferable, and no cash alternative will be offered. In the event that the prize cannot be supplied, no liability will be attached to www.scubaverse.com. When prizes are supplied by third parties, www.scubaverse.com is acting as their agents and as such we exclude all liability for loss or damage you may suffer as a result of this competition. Your information will be shared with the competition's sponsor unless you tick the opt out box. This competition closes on 09/12/20. The winner will be notified by email. The Editor-in-Chief’s decision is final.

  • The following fields are optional, however if you fill them in it will help us to determine what prizes to source in the future.

  • Date Format: MM slash DD slash YYYY
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Dive Training Blogs

5 Easy Steps For Choosing A Scuba Diving Center You’ll LOVE! (Watch Video)

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How do you pick which dive operation wins your money for your scuba diving vacation? If you only get to dive on vacation, you want to make sure you’re getting your money’s worth and getting experiences you enjoy. That’s why we are giving you our easy 5-step process for filtering out dive centers and narrowing down your selection to find the scuba team you want to be diving with!

In this example–driven video, we are showing you our procedure for how we pick our scuba dive operator. In this case, I use the island of Barbados, as I’ve actually never been scuba diving there.

THANK YOU so much to EVERYONE who is a part of this great community. We promise we have so much more planned for this channel. We’re going to keep spreading information and positivity to the Scuba Divers around the world! IMPROVE. INSPIRE. EXPLORE.


Subscribe here: http://bit.ly/DiversReady

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Spend 7 nights at the Cinco Plazas Apartments, Lanzarote with flights and 5 days diving from just £625pp with Diverse Travel this winter.  Travel 12th November - Spaces are limited - contact us now to book. Other dates available.

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