Chiton glaucus

Chiton glaucus
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Polyplacophora
Order:	Chitonida
Family:	Chitonidae
Genus:	Chiton
Species:	C. glaucus
Binomial name
	Chiton glaucus; (Gray, 1828)
Synonyms
	Amaurochiton glaucus(Gray, 1828) ;

Last updated August 19, 2023

Chiton glaucus, common name the green chiton or the blue green chiton, is a species of chiton, a marine polyplacophoran mollusk in the family Chitonidae, the typical chitons. It is the most common chiton species in New Zealand. Chiton glaucus is part of a very primitive group of mollusc with evidence of being present in up to 80 million years of the fossil record.

Description

Chiton glaucus are oval in shape, with a slightly elevated yet definite ridge running down the back of the organism. This results in a bilateral symmetry. The size of the organism is commonly 30-35 mm long.^[2]

Taxonomists primarily use characteristics of the valves and the girdle to tell the difference between species and this is the case for Chiton glaucus.^[3] The shell consists of eight overlapping valves. It is fairly large, up to 55 mm in length, with 6 intermediate valves between 2 terminal valves at either end of the organism. These valves are surrounded by a girdle, which helps with adhesion to the preferred surface and in the case of Chiton glaucus it is covered in large scales.^[2]

The valves and girdle are generally uniform in a green colour, but individuals brown, buff and even light blue have been known to be found, especially in the North of New Zealand. This is sometimes combined with individuals who lighter chevron or zig zag markings.^[2] Underneath the body of the chiton, there is a large foot which spans its total length.^[4] This is used to keep suction onto the chosen substrate. Gills are not obvious, instead being found in a set on either side of the foot.^[4] It has a small mouth at one end of the foot, however the mouth is merely a simple cavity.^[4]

Distribution and habitat

Within New Zealand, Chiton glaucus is found on the North, South and Stewart Islands, as well as the Chatham Islands.^[2] It is also present in Tasmania, becoming very common in estuaries.^[5] It is thought to have been introduced by shipping activity between Australia and New Zealand.^[2]

Chiton glaucus are found on rocky substrates with rocky tide pools forming a main portion of their habitat.^[6]Chiton glaucus are found in intertidal or subtidal zones in a broad range of environments including shores open to the elements to sheltered estuarine sites.^[2] In estuarine sites Chiton glaucus are found under bivalve shells and stones, particularly cockles as to avoid visual predators during daylight hours.^[2] This is compared to being found on stones and cobbles in more exposed areas.^[2] This chiton is able to survive in muddy areas, particularly estuaries.^[7] Surprisingly it is also able to live in areas were the substrate is semi-polluted.^[7]

Life cycle

Little is known about the habits of chiton in general but observations have been made to further understand the processes relating to spawning amongst other processes.^[4] Early research conducted by a member of the great barrier reef investigation in Queensland saw that a common chiton of this area seemed to every time choose a night of full moon to conduct its spawning.^[4] This also depended on the conditions at the time as if they were not favourable or the sea was rough, spawning would not occur and was delayed until the next full moon. This was the case even if in between full moons was a favourable time period where the weather was right.^[4] It has since been shown that the spawning of chiton is usually synchronous but not necessarily correlated with any particular stage of the lunar or solar cycle.^[8]

Generally chitons have separate sexes and sperm and eggs are spawned through a simple gonad near the posterior end of the foot.^[8] Chitons do not have a free swimming larval stage so distribution of the organism is not particularly great.^[4] Once the egg has been released through the anus it moves through currents into plankton where it hatches after about 2 days.^[8] Next metamorphosis occurs to promote larval settlement. The changes are not dramatic but it does start the biomineralisation of the valves and radula present in the adult stage.^[8] After this the prototroch and apical tuft are cast off and the shape of the organism changes from elongated to oval in outline about 0.5 mm in length with only seven calcareous valves.^[8] A month later the eighth valve becomes apparent and two red larval spots present themselves which are lost when the organism reaches maturity.^[8] The process then repeats if the organism reaches maturity through avoiding both invertebrate and vertebrate predators.

Diet

Chiton glaucus show clear daily patterns of activity; they remain hidden during the day to escape visual predators and then during the night they travel to the tops of the rock to feed on the algae that has grown there since the previous night.^[8]

According to research done by Robert Creese who analysed the contents in the gut of C. glaucus it was found that the main component of its diet is that of coralline algae. Other research suggests a broader range of organisms within its diet including encrusting organisms (sponges, bryozoans etc.) and on diatoms and algae in a grazing type method.^[2]

Predators, parasites, and diseases

They have a variety of predators both invertebrate and vertebrate including sea stars, crabs, sea snails, birds, and fish.^[9] One of the main predators of green chiton are oystercatchers.^[8] All species of New Zealand oystercatchers prey on chiton from rocky shores. The birds have adopted a technique where they first, strike a sharp angled blow on the shell plates and if this does not dislodge the organism then the bird will apply pressure on the margin between the foot and the rock surface and use a scissor-like motion to release the grip.^[10] This is done until the organism is separated from the surface, and after the valves are taken off by the oystercatcher the chiton is eaten in one piece.^[10]

Many species of chiton are susceptible to the parasite Minchinia chitonis .^[11] This releases spores into all tissue types of the chiton. It is unknown how, but the parasite is able to travel through the digestive tract and be excreted to prey on other chiton individuals.^[11]

Research

Recent analysis of the ultra structural and mechanical properties of the teeth present in that of Chiton glaucus and other organisms in the class Polyplacophora, one of the seven classes of mollusks, have shown to exhibit teeth of the most hardness and stiffness of any biomaterials known to date. This translates to as much as three times as hard as human enamel and the carbonate based shells of other mollusks.^[12] They achieve this feat through arranging a hard shell of organic incased and highly orientated magnetite rods that surround a soft core of organic rich iron phosphate in such a way that results in a tooth that is tough and wear resistant.^[13] By microscopically and spectroscopically analysing ultra structural features to figure out the structure/mechanical property relationships we can further our understanding relating to the architecture within the chiton tooth. The result of this would be wear resistant materials which could be developed for use in machines and tools, or coatings on medical implants and equipment.^[13]

Chiton living on open coastlines are brighter in colour. They have richer greens, yellows and blues, compared to those found in estuaries.^[7]

Related Research Articles

The radula is an anatomical structure used by mollusks for feeding, sometimes compared to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food enters the esophagus. The radula is unique to the mollusks, and is found in every class of mollusk except the bivalves, which instead use cilia, waving filaments that bring minute organisms to the mouth.

<span class="mw-page-title-main">Chiton</span> Class (Polyplacophora) of marine molluscs

Chitons are marine molluscs of varying size in the class Polyplacophora, formerly known as Amphineura. About 940 extant and 430 fossil species are recognized.

A tide pool or rock pool is a shallow pool of seawater that forms on the rocky intertidal shore. These pools typically range from a few inches to a few feet deep and a few feet across. Many of these pools exist as separate bodies of water only at low tide, as seawater gets trapped when the tide recedes. Tides are caused by the gravitational pull of the sun and moon. A tidal cycle is usually about 25 hours and consists of one or two high tides and two low tides.

The pied oystercatcher is a species of oystercatcher. It is a wading bird native to Australia and commonly found on its coastline. The similar South Island pied oystercatcher occurs in New Zealand.

The common periwinkle or winkle is a species of small edible whelk or sea snail, a marine gastropod mollusc that has gills and an operculum, and is classified within the family Littorinidae, the periwinkles.

The gumboot chiton, also known as the giant western fiery chiton or giant Pacific chiton, is the largest of the chitons, growing to 36 cm (14 in) and capable of reaching a weight of more than 2 kg (4.4 lb). It is found along the shores of the northern Pacific Ocean from Central California to Alaska, across the Aleutian Islands to the Kamchatka Peninsula and south to Japan. It inhabits the lower intertidal and subtidal zones of rocky coastlines. The gumboot chiton's appearance has led some tidepoolers to refer to it, fondly, as the "wandering meatloaf". The name "gumboot chiton" seems to derive from a resemblance to part of a rubber Wellington boot or "gum rubber" boot.

The Patellogastropoda, common name true limpets and historically called the Docoglossa, are members of a major phylogenetic group of marine gastropods, treated by experts either as a clade or as a taxonomic order.

The pie crust crab, is a species of crab found around New Zealand and south-eastern Australia.

Acanthochitona zelandica is a species of chiton in the family Acanthochitonidae, also sometimes known as the hairy, or "tufted," chiton. It probably developed during the mid to late Pleistocene, and is endemic to New Zealand.

Mopalia muscosa, the mossy chiton, is a species of chiton, a polyplacophoran, an eight-plated marine mollusk. It is a northeastern Pacific species which occurs from British Columbia, Canada, to Baja California Mexico.

Acanthopleura granulata, common name the West Indian fuzzy chiton, is a medium-sized tropical species of chiton. This type of chiton's activity does not depend on spring-neap oscillations leading to lower locomotion loss. Its morphology is different from usual chitons as it has a fifth valve, which is split into halves.

Lottia gigantea, common name the owl limpet, is a species of sea snail, a true limpet, a marine gastropod mollusc in the family Lottiidae. Its genome has been sequenced at the Joint Genome Institute.

Acanthochitonidae is a family of marine mollusks belonging to the class Polyplacophora, commonly known as chitons. Species are widely distributed throughout the world's oceans, but are most commonly found in the shallow waters of the Pacific Ocean, from Alaska to Chile.

Mopalia ciliata is a chiton in the genus Mopalia, commonly known as the hairy chiton. It is a medium-sized marine mollusc up to 5.0 cm (2.0 in) in length. It is oval shaped with 8 separate, moderately elevated, overlapping ridged valves on its dorsal surface. Hairy chitons can be found along the coast of North America.

Katharina tunicata is commonly known as the black Katy chiton, black Leather chiton, black chiton, or leather chiton,, is a species of chiton in the family Mopaliidae.

Plaxiphora albida, the white Plaxiphora chiton, is a species of chiton in the family Mopaliidae.

<span class="mw-page-title-main">Tidepool sculpin</span> Species of fish

The tidepool sculpin is a fish species in the sculpin family Cottidae that ranges from the Bering Sea to southern California. Individuals reach up to 8 cm (3 in) in length and are common in tidepools.

Plaxiphora obtecta is a large chiton in the family Mopaliidae, endemic to New Zealand, where it is most often found on the West Coast of the North Island. It is called Haka-hiwihiwi by some Māori and was likely a food source.

Acanthopleura echinata is a Southeast Pacific species of edible chiton, a marine polyplacophoran mollusc in the family Chitonidae, the typical chitons.

Acanthochitona crinita is a species of marine chiton in the family Acanthochitonidae. It is found on rocky coasts in the northeastern Atlantic Ocean, the North Sea and the Mediterranean Sea.

References

1 2 "Chiton (Chiton) glaucus Gray, 1828". www.marinespecies.org. Retrieved 2019-05-24.
1 2 3 4 5 6 7 8 9 Creese, Robert G. (September 1988). "Ecology of molluscan grazers and their interactions with marine algae in north‐eastern New Zealand: A review". New Zealand Journal of Marine and Freshwater Research. 22 (3): 427–444. doi:10.1080/00288330.1988.9516314. ISSN 0028-8330.
↑ Creese, R. G. (2010). Cook, Steve de C. (ed.). New Zealand coastal marine invertebrates. Archer, Danielle (illustrator). Christchurch, N.Z.: Canterbury University Press. pp. 298–314. ISBN 9781877257605. OCLC 456176240.
1 2 3 4 5 6 7 Powell, A. W. (1961). Shells of New Zealand . In A. W. Powell, Shells of New Zealand (pp. 28-30). Auckland: Whitcome and Tombs Limited.
↑ Grove, S.J., S. J. (2018). "Chiton glaucus". Molluscs of Tasmania. Retrieved 2019-05-24.
↑ Lindberg, D. L. (2007). Molluscs. In U. o. California, Encyclopedia of Tidepools and Rocky Shores (pp. 374–380). Berkeley: University of California Press.
1 2 3 Morley, Margaret S. (2004). A photographic guide to seashells of New Zealand. Anderson, Iain A. Auckland, N.Z.: New Holland. ISBN 1869660447. OCLC 56646921.
1 2 3 4 5 6 7 8 Eernisse, D. J. (2007). Chitons. In U. o. California, Encyclopedia of Tidepools and Rocky Shores (pp. 127-132). California: University of California Press.
↑ Creese, R. G. (2010). New Zealand Coastal Marine Invertebrates. In S. d. Cook, New Zealand Coastal Marine Invertebrates (pp. 298–314). Christchurch: Canterbury University Press.
1 2 Knox, G. A., Stonehouse, B., & B, W. H. (1974). Prey of New Zealand Oyster Catchers. Journal of the Ornithological Society, 288.
1 2 Bradbury, Phyllis C. (1994). "Parasitic protozoa of molluscs and crustacea.". Parasitic protozoa. Academic Press. pp. 139–264.
↑ Weavera, J. C., Wanga, Q., Miserezb, A., Tantuccioc, A., Strombergd, R., Bozhilove, K. N., et al. (2010). Analysis of an ultra hard magnetic biomineral in chiton radular teeth. Materials Today , 42-52.
1 2 Grunenfelder, L. K., Escobar de Obaldia, E., Wang, Q., Li, D., Weden, B., Salinas, C. W., et al. (2014). Stress and Damage Mitigation from Oriented Nanostructures within the Radular Teeth of Cryptochiton stelleri. Advanced Functional Materials , 6093–6104.