CLASSIFICATION OF LINGULA
PHYLUM :- BRACHIOPODA (Lophophore contains coiled arms.)
CLASS :- LINGULATA (Shell valves without hinge.)
ORDER :- LINGULIDA (Pedicel passage formed by both shells.)
FAMILY :- LINGULIDAE
Genus : Lingula
HABIT AND HABITAT
Lingula’s dozen living species are limited to the tropical and sub-tropical waters of the Indo-West Pacific area living in vertical burrows in sandy survibottom.
GENERAL CHARACTERSTICS OF LINGULA
- It has great evolutionary significance that it has survived for long 350,000,00 years.
- Animal consists of stalk and shell valves and remains erect in the burrows.
- When not disturbed, it protrudes through the shell, with valves slightly opened.
- Two valves are nearly equal and convex and contain setae.
- Lophophore is of the spirolophous type.
- Digestive gland opens by 4 ducts into the stomach. Intestine is longest in brachiopods.
- Sexes are separate.
- Japanese eat Lingula.
SPECIAL FEATURES
Lingula has long been considered an example of a living fossil, in fact, the perceived longevity of this genus led Darwin to coin this concept. This living fossil status is now considered unjustified. This status is based on the shape of the shell only, and it has been shown that this shape corresponds to a burrowing lifestyle, occurring in different brachiopod lineages, with different and evolving internal structures.
IDENTIFICATION
- It has stalk and two equal shell valves and all above features is Lingula.
REFERENCES
- http://vianetconchology.com/index.php
- https://en.wikipedia.org/wiki/Lingula_(brachiopod)
- Book of Practical Zoology VERTEBRATE by S.S.LAL – Rastogi Publications.