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Tentacle

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Tentacle

Cuttlefish with 2 tentacles and 8 arms

In touch, vision, or to the smell or taste of particular foods or threats. Examples of such tentacles are the "eye stalks" of various kinds of snails. Some kinds of tentacles have both sensory and manipulatory functions.

The word tentillum literally means "little tentacle". However, irrespective of size, it usually refers to a side branch of a larger tentacle. In some cases such tentilla are specialised for particular functions; for example, in the Cnidaria tentilla usually bear cnidocytes,[1] whereas in the Ctenophora they usually bear collocytes.[2][3]

Contents

  • Invertebrates 1
    • Molluscs 1.1
    • Cnidarians 1.2
    • Bryozoan 1.3
    • Trypanorhynch cestodes 1.4
  • Amphibians 2
  • Mammals 3
  • References 4
  • External links 5

Invertebrates

Molluscs

Front view of land snail showing upper and lower sets of tentacles
Abalone showing pallial tentacles

Many molluscs have tentacles of one form or another. The most familiar are those of the pulmonate land snails, which usually have two sets of tentacles on the head: when extended the upper pair have eyes at their tips; the lower pair are chemoreceptors. Both pairs are fully retractable muscular hydrostats, but they are not used for manipulation or prey capture.

Some marine snails such as abalone and top snails, Trochidae, have numerous small tentacles around the edge of the mantle. These are known as pallial tentacles.[4]

  • Tentacle- About.com
  • Enclopaedia Britannica
  • Cephalopods

External links

  1. ^ Marine Species Identification Portal : Zooplankton of the South Atlantic Ocean : Glossary : tentilla. Species-identification.org. Retrieved on 2013-05-02.
  2. ^ Harmer, Sir Sidney Frederic; Shipley, Arthur Everett et al. (1906) The Cambridge natural history Volume 1, Protozoa, Porifera, Coelenterata, Ctenophora, Echinodermata. Macmillan Company.
  3. ^ Mackie G.O., Mills C.E., Singla C.L. (1988). (Ctenophora, Cydippida)"Euplokamis"Structure and function of the prehensile tentilla of (PDF). Zoomorphology 107 (6): 319.  
  4. ^ a b c d Boumis R (2013). "Animals With Tentacles". Pawnation. AOL Inc. Retrieved 2013-06-08. 
  5. ^ Cooke, A. H.; Shipley, Arthur Everett et alia: The Cambridge natural history Volume 34, Molluscs, Trilobites, Brachiopods etc. Macmillan Company 1895
  6. ^ Bird J (5 June 2007). "CNIDARIANS: SIMPLE ANIMALS WITH A STING!". oceanicresearch.org. Oceanic Research Group. Retrieved 2013-06-08. 
  7. ^ Kosner AW (10 July 2012). "Lion's Mane Jellyfish Image: This Is (Literally) How Things Blow Up On The Internet!". Forbes. Forbes.com LLC™. Retrieved 2013-06-08. 
  8. ^ Wild Facts (29 November 2011). "Wild Fact #419 – One Large Jelly – Lion’s Mane Jellyfish". wild-facts.com. Retrieved 2013-06-08. 
  9. ^ Claus N (May 2013). "Bryozoa (Ectoprocta: ‘Moss’ Animals)". els.net. eLS. John Wiley & Sons Ltd.  
  10. ^ Beveridge, I., Bray, R. A., Cribb, T. H. & Justine, J.-L. 2014: Diversity of trypanorhynch metacestodes in teleost fishes from coral reefs off eastern Australia and New Caledonia. Parasite, 21, 60. doi:10.1051/parasite/2014060 PubMed

References

[4] The

Mammals

The legless amphibians called caecilians have two short tentacles, one on each side of the head, between their eyes and nostrils. The current opinion is that these tentacles supplement the normal sense of smell, possibly for navigation and to locate prey underground.[4]

Amphibians

Trypanorhynch cestodes are parasitic in fish. Their scolex shows four tentacles which are covered by spines. These tentacles help the adult cestode to attach to the intestine of the shark or ray that they parasitize. The same tentacles are also present in the larvae.[10]

A larva of trypanorhynch cestode (only two tentacles shown). Scale-bar: 0.1 mm

Trypanorhynch cestodes

Bryozoa (moss animals) are tiny creatures with tentacles around their mouths. The tentacles are almost cylindrical and have bands of cilia which create a water current towards the mouth. The animal extracts edible material from the flow of water.[9]

Bryozoan

The tentacles of the Lion's mane jellyfish may be up to 120 feet (37 meters) long. They are hollow and are arranged in 8 groups of between 70 and 150. The longer tentacles are equipped with ctenophores whose venom paralyses and kills prey. The smaller tentacles guide food into the mouth.[7][8]

Cnidarians, such as jellyfish, sea anemones, Hydra and coral have numerous hair-like tentacles. Cnidarians have huge numbers of cnidocytes on their tentacles. In medusoid form, the body floats on water so that the tentacles hang down in a ring around the mouth. In polyp form, such as sea anemone and coral, the body is below with the tentacles pointed upwards. Many species of the jellyfish-like ctenophores have two tentacles, while some have none. Their tentacles have adhesive structures called colloblasts or lasso cells. The colloblasts burst open when prey comes in contact with the tentacle, releasing sticky threads that secure the food.[6]

Cnidarians

The tentacles of the giant squid and colossal squid have powerful suckers and pointed teeth at the ends. The teeth of the giant squid resemble bottle caps, and function like tiny, hole saws; while the tentacles of the colossal squid wield two long rows of swiveling, tri-pointed hooks.

[4]

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