SCUBA News 273
(ISSN 1476-8011)
April 2023

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SCUBA News (ISSN 1476-8011)
Issue 273 - April 2023
https://www.scubatravel.co.uk
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Welcome to SCUBA News. Thanks for subscribing. Our "creature" of the month today was prompted by a chance find on a beach and subsequent investigation. Any sea creature questions - email news@scubatravel.co.uk.

What's New at SCUBA Travel?

	9 Best Dives in the Med Wrecks, walls, caves and canyons - but which are the best sites? SEE AND VOTE…
	Perfect Palau World-class diving with sea walls, sheer drop-offs, caves and an exuberance of marine life as her entire waters are a marine reserve. And sharks. Lots of them. LEARN MORE…
	Exploring the Underwater Treasures of Greece With 40 diving islands plus the mainland coast, there is plenty to choose from in Greece READ MORE…

10 Last Minute & Early-Bird Liveaboard Deals - Save up to $1688 US

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3. Red Sea Blue Force 2, Egypt, Extended North Route & The North Route, Save 10% on selected trips in April and May 2023 (9 nights), Price from USD 3,150 per trip per person
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Common Squid and their egg "mop heads"

"What is this" I was asked last week. Found on a Belgium beach this jellyish mop-head was the size of a dinner plate. The answer is a mass of squid eggs.

Eggs from several mothers...

Further investigation revealed fascinating facts. This bundle of eggs was not laid by one mother but by several. What happens is that the squid gather together at their mating spot. Males perform various displays to attract potential females, internally fertilizing them when accepted. The females then descend to the bottom and use their arms to deposit their egg capsules onto the communal egg mass. This egg mass is attached to a rock or other hard substrate on the sea floor.

...and many fathers

Some males spend considerable energy and time courting and defending individual females, and they have high mating success. Other smaller males behave more sneakily. A female's egg capsule can contain eggs fertilized by two, three or more males.

Each egg capsule has around 200 eggs in it. A female deposits 20 to 50 egg capsules at any one time. The egg capsules are drawn by the female into her arms before depositing them into the mass. They can lay eggs in bouts several days or weeks apart.

Why were they on the beach?

The egg capsule masses are negatively bouyant which helps prevent them washing up onto shore should they become detached. Some still do though. These were probably deposited not too far away.

Squid migrate to the coast to spawn. Spawning peaks in Spring, but depends on water temperature. The eggs need to be at between 12-24^oC to develop. Hatching takese place after about a month.

Strong swimmers, squid use their fins to swim like fish and their siphon to propel themselves very quickly forwards or backwards.

You find the Common or European squid (Loligo vulgaris ) from the North Sea down to the South African coast, including in the Mediterranean. It lives from 20 m down to around 500 m. The squid migrate from southern climbs in the winter up to Irish and North Seas in the summer.

Mollusca (Phylum) > Cephalopoda (Class) > Coleoidea (Subclass) > Decapodiformes (Superorder) > Myopsida (Order) > Loliginidae (Family) Loligo (Genus) > Loligo vulgaris (Species)

References

Hanlon, Roger. (1998). Mating systems and sexual selection in the squid Loligo: How might commercial fishing on spawning squids affect them?. California Cooperative Oceanic Fisheries Investigations Reports. 39. 92-100.

Ali Srairi et al, Reproduction of the squid Loligo vulgaris off the South Atlantic coast of Morocco

Vladimir Laptikhovsky et al, Spatial and temporal variability of spawning and nursery grounds of Loligo forbesii and Loligo vulgaris squids in ecoregions of Celtic Seas and Greater North Sea, ICES Journal of Marine Science, Volume 79, Issue 6, August 2022, Pages 1918-1930

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Diving news from around the World

	Scientists identify 2022 sea urchin killer The mass die-off of the long-spined sea urchin - a loss that threatens the health of coral reefs from the Caribbean to Florida's east coast - was caused by a one-celled organism called a ciliate.
	Mackerel is no longer a sustainable fish. Should you stop eating it? This seemingly abundant species was often touted as a responsible choice, but years of overfishing have led its sustainability rating to be downgraded
	Mexico takes aim against marine animals' trafficking but criminal networks persist Steps to protect the totoaba fish and vaquita porpoise come after the country was sanctioned, but they are being challenged by those intent on selling the fish.
	1,000 pounds of illegally caught sharks seized in Texas Roughly 1,000 pounds of illegally caught shark was seized by the U.S. Coast Guard this month.
	Coral-eating fish poo may act as probiotics for reefs Although coral-eating fish can cause damage to coral, their poo contains potentially beneficial bacteria
	Holiday makers must be alert to potential legal action over dolphin disturbance Changes to the UK regulations around jet ski use are a timely reminder to holiday makers and recreational water users to act responsibly around wildlife, or risk potential legal action.
	Maps of sharks' journeys show marine protected areas alone won't save them Scientists find that the sharks travel longer distances than previously known and spend long periods of time in unprotected areas that have a high degree of illegal, unreported and unregulated fishing.
	Protecting wildlife helps mitigate climate change Conserving wildlife across the world could significantly enhance natural carbon capture and storage, a new study has found.

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Photo credits: Tim Nicholson, Jill Studholme, Kristin Riser, Jianye Sui

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