Cirrothauma murrayi

Cirrothauma murrayi, the blind cirrate octopus,^[2] is a presumably blind octopus whose eyes can likely sense light, but not form images. It has been found worldwide, usually 1,500 to 4,500 metres (4,900 to 14,800 ft) beneath the ocean's surface, but a single specimen was collected in the Arctic immediately below the sea ice.^[3][4] Like other cirrates, it has an internal shell, muscular fins for swimming, and a web connecting the arms.^[5]

Cirrothauma murrayi
Conservation status
Data Deficient  (IUCN 3.1)[1]
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Order:	Octopoda
Family:	Cirroteuthidae
Genus:	Cirrothauma
Species:	C. murrayi
Binomial name
Cirrothauma murrayi Chun, 1911

The species was first caught by an expedition led by Sir John Murray in 1910, and it was later named in honor of Murray. It was described by German marine biologist Carl Chun in 1911.^[3][4]

The diet of this species is unknown, but like other cirrate octopods, the buccal mass, esophagus, and stomach of Cirrothauma murrayi suggest whole (but very small) organisms, especially small crustaceans, are part of its diet (it has only a vestigial trace of a radula).^[4] The enzymatic action of salivary excretions separates the crustacean's musculoskeletal attachments and allows for the tissue to be removed, leaving the exoskeleton of the crustacean undamaged.^[4]

Molecular work suggests that Cirrothauma murrayi may comprise two similar species^[6], indeed work on the species by Aldred et al. (1983) found that some specimens had sucker counts in the upper 30's per arm while others had counts around 60 per arm (despite the animals being similar in size), which may suggest two otherwise similar species^[4].

Description

Eye structure

The eye structure is very different from other octopods (and indeed the Cephalopoda as a whole). Their eyes are small, lens-less and presumably non-functional, as the eyes also lack irises and ciliary bodies.^[3] The eyes are embedded deep in the gelatinous tissue of their head.^[3]

Suckers

Cirrothauma murrayi has approximately 30 to 60 suckers per arm, the proximal 6 on each arm are sessile (without a stalk), but the remaining suckers out to the arm tips are highly modified, being minute and lacking a suction chambers, and are mounted atop elongate fleshy/gelatinous stalks.^[3][6]