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Ram horn shells are small, delicate spiral structures that beachcomers can commonly find around the world.
However, despite their ubiquity, the original owners of these shells are extremely elusive. Until now, we’ve never had footage of just one in the wild.
In the twilight zone of our oceans, at the fingertips of sunlight, a remote controlled vehicle (ROV) has now delivered the first footage of a ram’s horn squid (Spirula spirula) in its natural habitat.
This odd-looking cephalopod is a very small thing just 7 centimeters (less than 3 inches) long, with eight arms, two tentacles, a pair of bulging eyes, and an overall muppet-like appearance.
In its tail end, hidden under its mantle, is a tightly coiled inner shell equipped with gas chambers that the animal manipulates for flotation.
At first, the researchers who ran the ROV at the Schmidt Ocean Institute had no idea what they were watching.
“What the hell?” A scientist can be heard exclaiming in the background of the video, which was shot live on the Great Barrier Reef at a depth of approximately 850-860 meters (2,790 feet).
Exciting news! This appears to be the FIRST observation of Spirula, aka ram’s horn squid, alive + in its natural environment. Seen or very rarely captured, they have many extinct relatives, but are only living members of the genus Spirula, the family Spirulidae, and the order Spirulida. 1/3 pic.twitter.com/re4rZyRuER
– Schmidt Ocean (@SchmidtOcean) October 27, 2020
The rare sighting has since been shared online and has been confirmed to be the first live footage Spirula deep in the sea, the largest and least explored habitat on our planet.
Although there are numerous deep-sea species never seen before in their natural waters, this recent chance encounter has wowed scientists.
OH MY GOD! Okay, I don’t want to get too excited … but according to several squid experts, this could be the FIRST VIDEO OF A LIVE COPPER-HORN SQUID! While these squid have many extinct relatives, they are the only ones left of their species and have a coiled shell!
🎥@SchmidtOcean #DailyJelly pic.twitter.com/0Lv6ESvYNI– Open Ocean Exploration (@RebeccaRHelm) October 27, 2020
The ram’s horn squid is rarely seen in the wild, and is one of the more unusual cephalopods out there.
Aside from cuttlefish, it is the only other known mollusk that contains an internal chamber shell to keep it floating. However, unlike cuttlefish, the skeleton of this squid is tightly wrapped; mollusks in Nautilus the genus also has similarly shaped shells, but they are found outside the animal.
“I’ve been looking for them for a long time,” zoologist Michael Vecchione, who studies midwater squid at the Smithsonian National Museum of Natural History, told ScienceAlert.
“I have no doubt it’s a Spirula. ”
While Vecchione regularly catches this species from the depths, sometimes hosting it in aquariums, he has never before seen footage of the squid in its natural habitat.
Not even Neige Pascal, who studies Spirula at the University of Burgundy in France. He told ScienceAlert that the video is “very emotional”.
Spirula shell. (Antonov / Public domain)
Aside from the sheer rarity of this encounter, there is one particularly striking aspect in the footage: the position of the animal itself, with its head and tentacles floating upright and its fins pointing downwards.
“Are we completely sure of the orientation of the shoot? If so, this is the king of the revolution,” Pascal told ScienceAlert.
“Many people are going crazy because their heads are raised”, adds Vecchione.
“And the reason they’re freaking out is because the shell with its buoyancy is at the other end of the squid. So you’d think the head, which is heavier, would be dangling.”
When placed in an aquarium, this is how the squid orientates itself. Its head is pointing downward and its tentacles pointing upward, so the species was thought to occupy the same position in the deep sea.
(Ewald Rübsamen / Public domain)
According to Vecchione, however, this assumption has a problem. The ram’s horn squid also has a light-generating organ, known as a photophore, which is located near the floating shell.
This means that if Spirula they hang with their heads down, that light would be pointing upwards, and this is very unusual for deep sea animals.
In the twilight zone of our oceans, predators often look up in the hope of catching a glimpse of the outline of a possible meal. Then the photophores help camouflage prey in the deep sea by washing their silhouettes with light. If that lamp points upward, that organ is not as useful.
There are many things we still don’t know Spirula, including how the species reproduces and where it lays its eggs, but how this squid orientates itself in the water is one of the biggest questions for Vecchione.
While he can’t be sure it’s floating with its tentacles always pointing upwards, he says the footage is good evidence that the squid does at least part of the time. We will need more observations to solve that mystery.
And the curiosities surrounding the ram’s horn squid don’t end there. When the creature finally ran away in the video, it looks like some ink was poured into the water; Vecchione is pretty sure it came from the squid – a possible diversion tactic for his escape.
Possible inking from Spirula spirula. (Schmidt Ocean Institute / YouTube)
“This is interesting because Spirula it has the mechanism to produce ink but is reduced in this species, as in other deep-sea species, “Vecchione told ScienceAlert.
“But that suggests it’s functional and they’re using it for defense.”
It may be our first time seeing a ram’s horn squid in its natural habitat, but it’s also the first time we’ve seen a mischievous ROV. Fair enough if they get wet.
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