Atlantic pygmy octopus
| Atlantic pygmy octopus | |
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Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Order: | Octopoda |
| Family: | Octopodidae |
| Genus: | Octopus |
| Species: | O. joubini
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| Binomial name | |
| Octopus joubini Robson, 1925
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The Atlantic pygmy octopus (Octopus joubini), also known as the small-egg Caribbean pygmy octopus, is a small species of
O. joubini often seeks shelter from predators in empty clamshells, cans or small openings, pulling the opening closed with its arms, combining sand and gravel to form a lid.
They are found in the Atlantic Ocean, particularly in the tropical waters of the Caribbean and the Gulf of Mexico. The first holotype was collected in 1929 by Guy Coburn Robson and became a key factor in distinguishing between O. joubini and the closely related Octopus mercatoris (or in some cases, an unidentified species referred to as Octopus sp. X).[4] Much of the information about O. joubini was obtained through laboratory studies of captive specimens and what little is known about their behavior in a natural environment is inferential.
Physical characteristics
O. joubini is red-orange in color which is caused by pigmented cells called chromatophores that are common in many animals. Compared to other species of octopus, the O. joubini color patterning is relatively less complex. They are capable of becoming a dark, light, or intermediate shade ranging from brown to orange. As hatchlings, their chromatophores can also appear yellow.[4]
Though research is limited, some studies suggest that O. joubini have a complex system of sensory cells along their lip that serve a chemotactic function. These cells are highly ciliated and contain high concentrations of sensory neurons, some of which are thought to act as mechanoreceptors, and some as chemoreceptors. These neurons are likely chemoreceptors, considering the species' benthic lifestyle and the advantages that come with chemotactic sensitivity.[5]
Habitat
O. joubini are found in the warm temperate to tropical waters of the Atlantic, thriving in temperatures ranging from 18 to 25 °C (64 to 77 °F). They are benthic and are typically found on soft, muddy substrates around 10 to 15 m (33 to 49 feet) deep.[4][6] Many laboratory experiments have shown that O. joubini prefer to remain hidden or, in the case of a tank environment, close to the sides of the enclosure. This behavior is presumably for protection against outside predators, though no literature describes specific predators of the O. joubini.[7] In many instances, O. joubini observed in their natural habitat are found hidden in empty soda cans, and some researchers even obtained them by collecting soda cans from the ocean floor.[4][7]
Reproduction
O. joubini in captivity exhibit highly varied broods ranging from 140 to over 2,500 eggs. They can reach sexual maturity a very small size, though most spawning adults were at least 30 mm (1.2 inches). Females typically began to lay a new set of eggs when the oldest eggs began to hatch.[4]
The key characteristics that differentiate O. joubini from O. mercatoris, and other unidentified pygmy octopuses, is the size of the eggs and its color. While varying in size, fully developed eggs range from 2.9 to 4.8 mm (0.11 to 0.19 inches), and are overall smaller than other species that were studied, informally referring to them as the "small egg species" that is most representative of the original O. joubini Robson holotype. Additionally, O. joubini appear to have a reddish-orange color that is more distinct than the larger egged species.[4]
Life cycle
Females of this species breed between March and June, laying elliptical, amber eggs in a sheltered place. The hatchlings are relatively small (0.04 grams or 0.62 grains), but are fully formed and can hunt within hours. They reach maturity in around 182 days and weigh about 30 grams (1.1 oz) at this time.[8]
Hatchlings go through a brief
Diet
Like all octopuses, O. joubini is
Behavior
Though octopuses are solitary animals, they do appear to partake in various social interactions, especially when living in high densities or in limited space (as in a laboratory environment). O. joubini demonstrate loose dominance relationships where larger octopuses would take over a particular area. However, O. joubini do not isolate themselves and are often attracted to spaces where there are others and will often share spaces, suggesting that they are not territorial.[7] They are also more likely to fight with other species, rather than with each other, when competing for space.[9]
Threats
In addition to competition and presumed predation, O. joubini also have to deal with anthropogenic threats such as pollution. In 1999, a harmful algal bloom wiped out an entire population of Octopus mercatoris in St Joseph's Bay, Florida. After five years only one brooding female was collected, demonstrating the long term impact these blooms can have on species. Though research indicated that only the species O. mercatoris was affected, the predicament of this algal bloom could foreshadow possible threats to O. joubini, and other species, where pollution could cause more severe and frequent algal blooms.[6]
References
- doi:10.2305/IUCN.UK.2018-2.RLTS.T162911A952525.en. Retrieved 29 January 2023.)
{{cite journal}}: CS1 maint: multiple names: authors list (link - ISBN 3-925919-32-5. Retrieved 4 January 2023.
- ^ "Octopuses and Squids". Gulf Specimen Marine Laboratory. Archived from the original on 25 February 2007.
- ^ ISSN 0952-8369. Retrieved 4 January 2023.
- S2CID 3012505. Retrieved 4 January 2023.
- ^ . Retrieved 4 January 2023.
- ^ S2CID 53169231.
- KiB).
- ISSN 0091-181X.
External links
- "CephBase: Atlantic pygmy octopus". Archived from the original on 17 August 2005.