Acanthopleura granulata

Acanthopleura granulata, common name the West Indian fuzzy chiton (also known as Curbs or Sea Cradles),[1] 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.[2] Its morphology is different from usual chitons as it has a fifth valve, which is split into halves.[3]

Acanthopleura granulata
Live individual on a rock in Guadeloupe
Scientific classification
Kingdom:
Animalia
Phylum:
Mollusca
Class:
Polyplacophora
Order:
Neoloricata
Family:
Chitonidae
Genus:
Acanthopleura
Species:
A. granulata
Binomial name
Acanthopleura granulata
(Gmelin, 1791)
Synonyms

Chiton granulatus Gmelin, 1791, Chiton blauneri Shuttleworth, 1856

This species is common within its range in the tropical Western Atlantic, but it is often not noticed, because its color and texture are similar to the rocks on which it lives. With not many predators the West Indian fuzzy chiton can live up to 40 years. [1]

In countries that used to be part of the British West Indies, these and other common intertidal chitons are known as "curb"; the foot of the animal is eaten by people and is also used as bait for fishing.

Museum specimen of Acanthopleura granulata from Barbados

Description

This species of chiton grows to be about 7 cm (2.8 in) in length.[4] The girdle is densely spiky and usually has a few black bands.

The surface of the valves (or plates) in this species is almost always heavily eroded in adults, but when not eroded, the valve surface is granulated. The valves are thick and heavy. The morphology of the West Indian Fuzzy Chiton contains a fifth valve, split into two symmetrical half valves that are independent to each other and other valves. A gridle-like tissue splits the valves.[3]

This specific type of chiton displays hundreds of shell eyes (< 100 µm) embedded in their dorsal shell. These eyes provide special vision, containing a retina, layer of screening pigment and a lens.[5]

Distribution

This chiton occurs from southern Florida to Mexico, south to Panama, and in the West Indies.[4][6]

They orient themselves, maintaining a constant zonal level, according to the exposure to wave action along the coastal shore line. This organization is due to their foraging behavior, which is limited to the nocturnal low tides.[2]

Ecology

This species lives on rocks very high in the intertidal zone.[7] It can tolerate a lot of sun. Feeding is primarily nocturnal as there are increased levels of Hsp70, heat shock proteins which protects the organisms from environmental stressors including high temperatures, in the foot muscle under natural night time conditions .[8] During the day, levels decrease again as the stress level protein follows the daily air temperature curve.[9] It feeds on several species of algae.[10]

  • Two valves of A. granulata, an intermediate plate (32 mm) and a tail plate (21 mm)
  • Two individuals of A. granulata in their natural habitat on a rock in Guadeloupe

References
  1. "The Fuzzy Chiton".
  2. Focardi, S., & Chelazzi, G. (1990). Ecological determinants of bioeconomics in three intertidal chitons (Acanthopleura spp.). Journal of Animal Ecology, 49(1), 347-362.
  3. Kingston, A., Sigwart, J., Chappell, D., & Speiser, D. (2019). Monster or multiplacophoran: A teratological specimen of the chiton Acanthopleura granulata (Mollusca: Polyplacophora) with a valve split into independent and symmetrical halves. Acta Zoologica, Acta Zoologica, 03/18/2019.
  4. Malacolog info
  5. Speiser, D., Demartini, D., & Oakley, T. (2014). The shell-eyes of the chiton Acanthopleura granulata (Mollusca, Polyplacophora) use pheomelanin as a screening pigment. Journal of Natural History, 48(45-48), 2899-2911.
  6. Catalogue of life
  7. SeaLifeBase
  8. Schill, R., Gayle, P., Fritz, G., & Köhler, H. (2008). Variability in the diurnal stress protein (Hsp70) cycle in tropical chitons (Acanthopleura granulata) from the intertidal zone: The influence of temperature and photoperiod exposure. Marine and Freshwater Behaviour and Physiology, 41(4), 229-239.
  9. Schill, R., Gayle, P., & Köhler, H. (2002). Daily stress protein (hsp70) cycle in chitons ( Acanthopleura granulata Gmelin, 1791) which inhabit the rocky intertidal shoreline in a tropical ecosystem. Comparative Biochemistry and Physiology, Part C, 131(3), 253-258.
  10. Glynn, Peter William On the Ecology of the Caribbean Chitons Acanthopleura Granulata Gmelin and Chiton Tuberculatus Linni: Density, Mortality, Feeding, Reproduction, and Growth Smithsonian Libraries
  • Gmelin, J.F., (1791). Caroli a Linné, Systema naturae per regna tria naturae. Editio decima tertia. Leipzig, Germany: 1(6) class 6, Vermes: 3021-3910
  • Abbott, R Tucker (1954). American Seashells. D. Van Nostrand Company Inc. xiv + 541 p. N.York.
  • Warmke, Germaine L. & Abbott, R Tucker. 1961. Caribbean Seashells. Livingston Publishing Company. Narbeth. Pennsylvania.
  • Speiser, Daniel I., Douglas J. Eernisse & Sönke Johnsen. 2011. A chiton uses aragonite lenses to form images. Current Biology, 21(8):665-670
  • Rodríguez, G. 1959. “The marine communities of Margarita Island, Venezuela”. Bulletin of Marine Science of the Gulf and Caribbean, Coral Gables, FL, 9(3): 237-280
  • Daniel I. Speiser, Daniel G. DeMartini & Todd H. Oakleya The shell-eyes of the chiton Acanthopleura granulata (Mollusca, Polyplacophora) use pheomelanin as a screening pigment
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