Figure 1: An illustration of a vampire squid (Vampyroteuthis infernalis), displaying its characteristic cloak, large eyes, detritus capturing filament, and bioluminescent tipped arms and complex bioluminescent photophores at the bases of the fins. (Photo Credit: Citron / CC-BY-SA-3.0)

Originally described in 1903 by German marine biologist Carl Chun as an octopus, and later classified as Vampyroteuthis infernalis, the ‘vampire squid from hell’, due to its devilish appearance. This name is rather misleading however, as this unique cephalopod, which is the lone member of its order, Vampyromorpha, is more mellow than its name suggests.

The vampire squid is neither a true squid, or true octopus. But is in fact believed to be an ancestral link between the two, as they share common characteristic traits. These small cephalopods only grow to a known maximum length of 28 cm, with their mantle making up to 12 cm of that, are typically found in tropical and temperate regions in the Pacific, Atlantic, and Indian Oceans from 600 to 1200 m in depth where little light reaches. Off the coast of California, USA in the Pacific Ocean above the Monterey Submarine Canyon, the vampire squid is found year-round inhabiting a zone known as the oxygen minimum layer, which has oxygen concentrations of 0.5 mg/L, a large difference from the typical ocean oxygen concentration range of 4 to 6 mg/L.

In these extreme conditions, phytoplankton productivity is typically high as well as carbon availability, which is usually too abundant for multicellular organisms to consume. So, bacteria occur in high concentrations on the organic matter, resulting in decomposition of the organic matter, thus creating the low oxygen levels the water column. Except for organisms such as copepods, cnidarians, and other cephalopods, these conditions cause great levels of stress and sometimes death for the large predator species. Because of this they tend to either avoid the areas of low oxygen or simply only migrate through, meaning they are in very low densities at these depths, making these a great refuge for the vampire squid. The vampire squid can survive at these conditions as it incorporates the respiratory protein haemocyanin, which creates a high affiliation with oxygen in its blood. In addition, it has the lowest mass-specific metabolic rate of any cephalopod, because of an adaptation which suppresses its aerobic metabolism, which makes it capable of surviving in such low oxygen conditions.

The unique physical characteristics of the vampire squid, some of which can be seen in figure 1 and the video below from a Nautilus dive in 2014, are the eight webbed arms, tipped with photophores, light producing organs, which are theorised to be used in anti-predation techniques, and if this doesn’t work it inverts its cloak to expose its suckers and finger like projections called cirri, creating the appearance of a spiky ball, making it unappealing to predators. As well as their photophore tipped arms the vampire squid is covered in pigment altering organs called chromatophores, as well as a pair of complex photophore organs at the base of their fins. Their large eyes, for which the vampire squid has the largest eye of any known animal relative to its body size, to maximise the light photons entering the eye at the dark depths they are found. Two retractable feeding filaments (more about that later), and the distinct brownish-red body colouration, which makes the squid appear practically invisible in the deep, camouflaging itself from predators.

Video Credit: EVNautilus

Originally believed to consume prey such as copepods, prawns, and cnidarians by enclosing them within their cloaked arms and passing them into their mouths, later research found that vampire squid have a unique feeding technique out of all known cephalopods. As they drift through the water with one of their two filaments extended out to capture falling organic particles called detritus or marine snow, meaning this is the first known detritovore cephalopod. This was further backed-up after detailed analysis of a number of specimens’ stomach contents, along with observational studies using remotely operated vehicles, or ROV’s, which can be seen in the video below from the Monterey Bay Aquarium Research Institute.

Video Credit: Monterey Bay Aquarium Research Institute (MBARI)

The vampire squid are one of the two known species of cephalopods that can reproduce multiple times in their life, the other being the chambered nautilus (Nautilus pompilius). Typically, cephalopods are semelparous, meaning they only reproduce once in their life and die soon after. Like other cephalopods, the male vampire squid using a modified arm to insert a sperm sac into a specialised cavity within the female’s mantle, which they can then store and use to reproduce. Following this, the female vampire squid will develop a batch of eggs, which it then spawns. Once they have spawned, instead of dying, the female returns to a resting reproductive state before creating a new batch of eggs. This reproductive cycle can be repeated up to at least 20 more times throughout its life. The life of a vampire squid in relation to other cephalopod species is quite long. The exact age that a vampire squid can reach is unknown, but fellow deep-sea squid species in the similar environments have found to be living to ages in excess of 3 years, with one deep-sea species, Graneledone boreopacifica being known to brood its eggs for up to 4 years, the longest of any cephalopod, which shows the extent of its life. This far exceeds the ages of shallow water coastal species, which typically do not exceed 1-2 years in age.

Human Impacts

Unfortunately, like most other marine species, the vampire squid is coming under threat from human intrusion, be that directly or indirectly. Threats such as ocean warming, and ocean acidification is reducing the oxygen concentration in the squids’ habitat, making it harder for organisms to survive. Overfishing and industrialisation are factors directly impacting the vampire squid, as the human population expands and is ploughing the depths for more food to feed the expanding population. There is some good in the gloom however, due to the unique charismatic appearance they are becoming prominent in the public eye and pop-culture, an example of this is the vampire squid appearing on the children’s show the ‘Octonauts’. This increasing popularity will hopefully encourage more people to want to protect it, and other animals within the deep from the such threats that we have produced.

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