Over the past couple weeks here at Divetech we have had multiple reports of a most exciting nature: the Caribbean Reef Squid (Sepioteuthis sepioidea) is back! With their compelling colour-changing displays and their impressive schooling formations, these squids have been long-time favourites of divers around the Caribbean. However, the squiggly cephalopods have been largely absent from our shores for around five months, having departed last year October. But where do they go? And what do we truly know about these tentacled molluscs?
Description
Describing the Reef Squid is the easy part. Fully grown, they are 15-30cm or 6-12 inches long. They have distinctly torpedo-shaped bodies which are placed above their head. This torpedo-shaped body can also be called the mantle, which contains various organs from gills and ink sacs to reproductive and digestive organs. Their fins run almost the entire length of the side of the mantle. Below that you have their heads with ten limbs attached to them – eight short arms by the mouth and two longer tentacles tucked inside. On either side of the head you have two very large complex eyes – squids tend to have some of the largest eye to body ratios in the animal kingdom! Caribbean Reef Squid tend to default to a mottled brown or green colouring at the top (dorsal) side of their body, leaving the underside (ventral) much lighter. This allows them to be camouflaged, depending on the direction a potential predator may be looking at them from.
Colour changes and communication
Like many cephalopods, the Caribbean Reef Squid can change its colours seemingly on a whim. These colours can be used for camouflage, but just as often are used for an entirely different function – communication! Have you ever passed close to a squid, only for it to become pale and zoom away? That is its “danger” shout. They have other colours for signalling slight alarm, seeing prey, readiness to mate and many more. They have such control over this method of communication that a squid can tell its friend to the right hand side something completely different to what it is currently telling the squid on the left!
Some of the many faces of the Caribbean Reef Squid
Feeding behaviour
The Caribbean Reef Squid is a carnivorous predator. They primarily hunt at night, though they may still store or feed on their prey during the daytime. Their favourite food is shrimp and small fish such as sardines or silversides, and they have developed all sorts of tricks to hunt them. For shrimp, the squid will descend over the sand and use its tentacles to stir up the substrate, flushing the shrimp out of its hole. For fish, they will disguise themselves as sargassum. They change their colour and texture to match that of the weed and use their tentacles to lure fish closer to them. Interestingly, squid tend to hunt alone but are not above alerting other squid in the area when they see prey.
Shoaling
Did you know? Despite pop culture trying for years to label a group of squid a ‘squad’, the official designation is still a ‘shoal of squid’. Within these shoals, squids tend to communicate extensively with one another and are generally very peaceful in their interactions, even during mating season. These shoals generally come together for protection, as well as foraging advantages, mating, and courtship. The shoals have a clear hierarchy, with the smaller squid giving way to the larger. The shoal will generally have ‘sentinels’, squid who are tasked with keeping watch for approaching predators. Each shoal generally has sentinels keeping an eye out in every direction at all times. When the shoal is threatened by a predator, the larger squid will often be the ones who go out to distract or threaten the would-be predator.
Mating – and why they are here now
It is easy to assume that when the squid disappear from our shores they are migrating elsewhere. However, the truth is that they are actually just living in the deeper waters of the open ocean down to about 150m or 500ft. Every year around February they will come shallower (1-12m or 5-40ft depths) for courtship and mating. This is the reason why we are able to see them now.
Their mating rituals are complex, and we are still trying to understand them. The males will often have to compete with 2-5 other males to mate with a female, and while the largest squid generally wins the females seem to be able to choose whether to accept a male to be their sexual partner or not. When a male wants to mate with a female, he will approach her and gently stroke her with his tentacles. The female may flash colours of alarm at this stage, but the male will generally try to soothe her by blowing jets of water onto her and swimming away and returning repeatedly, pulsing colours at her. This dance can last up to an hour before a female accepts a male. Once the male is accepted, he will display a pulsating pattern and attach a sticky sperm sack to the female. She will then take the sack and, if she wants to accept it, fertilises herself. She will then search for an appropriate place on the reef – somewhere relatively sheltered and hidden – where she can lay her eggs and pass away. The male will still have some time before he also dies, and can use that time to reproduce with other squids too before he joins her in a watery grave.
A pair of mating Caribbean Reef Squid
Baby squid in their eggs!
When Squids Fly
The Caribbean Reef Squid can launch itself 2m (6.6ft) out of the water, flying for 10m (30ft) before re-entry! This trait was discovered by marine biologist Silvia Marciá in 2001, and led to six more species of ‘flying squid’ to be discovered.
Despite all the research into these tentacular friends, there is always more to learn and discover about them. So come on over! See the squid that has captured the hearts and minds of divers for decades as they grace us with their presence for the next few months.
A special thanks to Everett Turner Jr for sharing his incredible squid photos with us!
