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Sepioloidea lineolata
Conservation status
	; Data Deficient (IUCN 3.1)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Order:	Sepiida
Family:	Sepiadariidae
Genus:	Sepioloidea
Species:	S. lineolata
Binomial name
	Sepioloidea lineolata; (Quoy & Gaimard, 1832)
Synonyms
	Sepiola lineolata; Quoy & Gaimard, 1832;

Sepioloidea lineolata or more commonly known as the striped pyjama squid or the striped dumpling squid is a type of bottletail squid^[3] that inhabits the Indo-Pacific Oceans of Australia. The striped pyjama squid lives on the seafloor, often hiding in the sand.^[4] When fully mature, a striped pyjama squid will only be about 7 to 8 centimetres (2.8 to 3.1 in) in length. Baby striped pyjama squid can be smaller than 10 millimetres (0.39 in).

Anatomy

The striped pyjama squid is able to disguise itself by changing its appearance. The squid will change to a dark brown or purple color when it is being attacked or to camouflage itself with the surrounding environment. Sepioloidea lineolata has two tentacles for feeding and eight arms. The mantle opening on the dorsal side is fringed with finger-like tendrils. They have a maximum mantle length of 40 mm.^[5] Like all members of its family, it lacks a shell.^[6] The squid's two feeding tentacles have suckers on them with toothed rims.^[7]

Sepioloidea lineolata also have glands underneath their body that can secrete a toxic slime whenever the squid is being attacked by a predator.^[8] The slime scares off the predators or allows the striped pyjama squid enough time to escape. Another defense mechanism that S. lineolata uses is its inking behavior. The ink that cephalopods produce is made of secretions from two different glands that is colored by melanin. The ink that is expelled can mimic the shape of the squid and thereby distract the predator long enough for the squid to get away, or it can interfere with the vision of the predator.^[9]

The striped pyjama squid has white and brown stripes all across its body. The white stripes on the squid are reflective of white light.^[10] The dark stripes are actually chromatophores, tiny sacs of pigment that the cuttlefish can flash.^[11] S. lineolata and other similar cephalopods are poisonous with the venom of their saliva containing tetrodotoxin, a type of neurotoxin.^[12]

Feeding

The striped pyjama squid is a predatory animal that feeds on fish, shrimp and crustaceans. During the day, Sepioloidea lineolata will bury itself in the sand to where only the top of its head and its yellow eye are visible. Throughout the day, the squid continues to flick sand particles over its body in order to remain hidden. Because the striped pyjama squid is almost always buried, its pupil is placed dorsally on its body. This also means that Sepioloidea lineolata have high density photoreceptors due to the increased eye movements.^[13]

Parasites

The striped pyjama squid has been found to be parasitized by dicyemids. Dicyemids are mesozoans, worm-like parasites that affect the renal appendages on cephalopods that live near the seafloor, like S. lineolata. These dicyemids are also usually host specific.^[14] Dicyemids are able to thrive inside the striped pyjama squid because the renal appendages are filled with fluid, which creates the perfect habitat for the parasite.^[15] Once inside S. lineolata, the dicyemid will receive its nutrition from the squid's urine.^[16]^[17]

Mating and reproduction

Sepioloidea lineolata reproduce sexually. In order to mate, a male striped pyjama squid will grasp a female striped pyjama squid and place her to where they are both head-to-head. The male squid then inserts a spermatophore, or a sperm packet, near where the female will store the sperm until she is ready to lay eggs. The male Sepioloidea lineolata can also remove sperm from another male if he detects it in the female. He removes the sperm using a specialized arm shaped like a spoon. Like many species in the order of Sepiida, the male usually dies after mating.^[18] The females lay their eggs soon after mating. They lay their eggs in batches or clumps under coral on the seafloor.

References

^ Barratt, I.; Allcock, L. (2012). "Sepioloidea lineolata". IUCN Red List of Threatened Species. 2012: e.T162499A903030. doi:10.2305/IUCN.UK.2012-1.RLTS.T162499A903030.en. Retrieved 1 May 2023.
^ Julian Finn (2016). "Sepioloidea lineolata (Quoy & Gaimard, 1832)". World Register of Marine Species. Flanders Marine Institute. Retrieved 8 February 2018.
^ Sanchez, Gustavo; Rokhsar, Daniel (2 June 2021). "Clarifying the evolution of bobtail and bottletail squid". Ecology & Evolution. Retrieved 4 December 2022.
^ Reid, Amanda (July 2016). Cephalopods of Australia and Sub-Antarctic Territories. CSIRO Publishing. p. 279. ISBN 9781486303946. Retrieved November 14, 2024.
^ Reid, Amanda (July 2016). Cephalopods of Australia and Sub-Antarctic Territories. CSIRO Publishing. p. 278-279. ISBN 9781486303946. Retrieved November 14, 2024.
^ Richard E. Young (15 August 2010). "Sepiadariidae (Naef, 1916)". The Tree of Life Web Project. Retrieved November 14, 2024.
^ "Striped Pyjama Squid". Oceana.
^ Caruana, Nikeisha J.; Cooke, Ira R.; Faou, Pierre; Finn, Julian; Hall, Nathan E.; Norman, Mark; Pineda, Sandy S.; Strugnell, Jan M. (2016). "A combined proteomic and transcriptomic analysis of slime secreted by the southern bottletail squid, Sepiadarium austrinum (Cephalopoda)". Journal of Proteomics. 148: 170–182. doi:10.1016/j.jprot.2016.07.026. PMID 27476034.
^ Derby, Charles (2014). "Cephalopod Ink: Production, Chemistry, Functions and Applications". Marine Drugs. 12 (5): 2700–2730. doi:10.3390/md12052700. PMC 4052311. PMID 24824020.
^ Bell, George R. R.; Mäthger, Lydia M.; Gao, Meng; Senft, Stephen L.; Kuzirian, Alan M.; Kattawar, George W.; Hanlon, Roger T. (2014). "Diffuse White Structural Coloration from Multilayer Reflectors in a Squid". Advanced Materials. 26 (25): 4352–4356. Bibcode:2014AdM....26.4352B. doi:10.1002/adma.201400383. PMID 24789321. S2CID 5241772.
^ Bryan, Candace (30 August 2017). "8 Facts About The Nap-Ready Striped Pyjama Squid". Azula.
^ Cooke, I.R.; Whitelaw, B.; Norman, M.; Caruana, N.; Strugnell, J.M. (2015). "Toxicity in Cephalopods". In Gopalakrishnakone, P.; Malhotra, A. (eds.). Evolution of Venomous Animals and Their Toxins. Springer, Dordrecht. pp. 1–15. doi:10.1007/978-94-007-6727-0_7-1. ISBN 978-94-007-6727-0.
^ Talbot, C. M.; Marshall, J. (2010). "Polarization sensitivity and retinal topography of the striped pyjama squid (Sepioloidea lineolata - Quoy/Gaimard 1832)" (PDF). Journal of Experimental Biology. 213 (19): 3371–3377. doi:10.1242/jeb.048165. PMID 20833931.
^ Catalano, Sarah R. (2013). "Population structure and species status of the giant Australian cuttlefish (Sepia apama) in Southern Australian waters as inferred from dicyemid parasite genetics". The South Australian Naturalist. 87 (1): 30–33.
^ Hidetaka Furuya and Kazuhiko Tsuneki "Biology of Dicyemid Mesozoans," Zoological Science 20(5), (1 May 2003). https://doi.org/10.2108/zsj.20.519
^ Catalano, Sarah R. (2013). "First descriptions of dicyemid mesozoans (Dicyemida: Dicyemidae) from Australian octopus (Octopodidae) and cuttlefish (Sepiidae), including a new record of Dicyemennea in Australian waters". Folia Parasitologica. 60 (4): 306–320. doi:10.14411/fp.2013.032. PMID 24261132.
^ Catalano, Sarah R.; Furuya, Hidetaka (2013). "Two New Species of Dicyemid (Dicyemida: Dicyemidae) from Two Australian Cephalopod Species:Sepioteuthis australis(Mollusca: Cephalopoda: Loliginidae) and Sepioloidea lineolata(Mollusca: Cephalopoda: Sepiadariidae)". Journal of Parasitology. 99 (2): 203–211. doi:10.1645/GE-3252.1. PMID 23020772. S2CID 12212459.
^ "Cephalopods". The Living World of Molluscs.