Planispiral is a condition in which a tubicolous shell is coiled in a single horizontal plane and the diameter increases away from the axis of coiling. This term is usually used for describing gastropod shells. Many cephalopods and tubeworms can also have a planispiral shell (Allaby and Allaby, 1999).
References[edit]
- Allaby, A. & Allaby, M. (1999). "Planispiral". A Dictionary of Earth Sciences. Retrieved 2014-01-13.
External links[edit]
Cephalopod anatomy | ||||||||||||||
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| Mantle & funnel |
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| Head & limbs |
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Developmental stages: Spawn → Paralarva (Doratopsis stage) → Juvenile → Subadult → Adult • Egg fossils • Protoconch (embryonic shell) | ||||||||||||||
Well, that’s interesting to know that Psilotum nudum are known as whisk ferns. Psilotum nudum is the commoner species of the two. While the P. flaccidum is a rare species and is found in the tropical islands. Both the species are usually epiphytic in habit and grow upon tree ferns. These species may also be terrestrial and grow in humus or in the crevices of the rocks.
View the detailed Guide of Psilotum nudum: Detailed Study Of Psilotum Nudum (Whisk Fern), Classification, Anatomy, Reproduction