Megabalanus tintinnabulum   (Linnaeus,  1758) (Barnacle)
Organism information awaits expert curation
Class: Maxillopoda

Image copyrights: Henry & McLaughlin

Size: Basal diameter 30-60 mm

Color: Coloration widely vary; rosy pink longitudinal stripes on parietes; dark brown stripes; parietes blackish purple. Radii darker than the parietes. In live animals tergo-scutal flaps erect with two to three brown bands; spaces between bands lighter brown, tinged with bright fluorescent green shade; inner shell margin pale white or light yellow.

Shell: Conical; when crowded tubulo-conical; orifice large and trigonal; margin irregularly crenated; shell surface longitudinally ribbed. Radii broad with oblique summits; finely striated transversely. Shell, opercular valves and basis massive and strong; alae smooth with summits parallel to the base.

Scutum: Triangular; transverse growth ridges prominent and every alternate or third ridge ends along the occludent margin into conspicuous hobs forming serrated edge helping opposed valves to close tight. Basitergal region angular; articular ridge broad, ending in a free point and half as long as highly reflexed tergal margin; articular furrow deep, broadened by articular ridge and slightly elevated tergal margin of the scutum; lateral depressor muscle pit well developed, adductor depressor muscle cavity broadly ovate and deep.

Tergum: Broad and triangular; external longitudinal furrow closed; apex bluntly produced; carinal portion of basal margin slightly excavated; scutal portion at right angles with the spur; scutal margin broadly reflex towards distinct and straight articular ridge, extending half way down to merge in the middle; articular furrow deep; tergal depressor muscles crests three to four; spur prominent, straight, obliquely truncated and situated close to basi-scutal angle. In older specimens spur relatively stouter and moderately longer and produced prominently for a considerable distance on the internal surface of the tergum.

Mouth parts - Labrum: With transverse, highly hairy crest, with a shallow median notch; in young, presence of teeth indicated by three chitinous points on either side of the crest. In older specimens one or two of these chitinous points reduced or absent. Lateral surface of the labrum with dense and obliquely directed setae.

Mandible: With five teeth, first tooth larger and sharply pointed; second and third usually bifid; fourth and fifth very much reduced; fifth teeth always bifid with a number of strong and short spines at lower half; upper margin arched with sparsely arranged setae; lower margin straight with dense setae; cutting edge armed with numerous spinules.

Inner maxilla: Rectangular; cutting edge, slightly depressed to form shallow central edge; upper pair of spines large, long and stout, followed by fourteen slender spines, placed in a double row decreasing in length downwards; below the central spines a pair of slender spines equal in length to the upper pair followed by minute spinules.

Phytoplankton and other organic matter are filtered from the water column by Megabalanus tintinnabulum for food.

The breeding season for Megabalanus tintinnabulum begins when water temperatures begin to rise. It is a hermaphrodite, but fertilization occurs by mating with another individual. Egg brooding and fertilization are internal, with larvae being released into the water column for a short period of time before they settle on the substrata.

Synonym (s)
Balanus tintinnabulum tintinnabulum Nilsson-Cantell, 1938
Balanus tintinnabulum tintinnabulum Stubbings, 1967
Balanus tintinnabulum var. communis Darwin, 1854
Megabalanus tintinnabulum Newman & Ross, 1976
Megabalanus tintinnabulum (Linnaeus, 1758)

Common Name (s)
• Acorn Barnacle (English)
Economic Importance and Threats
Importance:  Dangers
(Megabalanus tintinnabulum is a cosmopolitan fouling species, and one of the most common species of barnacle found fouling vessels.)

Habitat:  Rocky, Coastal


• Tamil Nadu, Pamban INDIA
• Tamil Nadu, Tharangambadi INDIA
• West Bengal, Digha INDIA
• Maharashtra, Mumbai INDIA
• Tamil Nadu, Krusadai Island INDIA
• Tamil Nadu, Periyamuttam INDIA
• Andaman and Nicobar Islands, Great Nicobar Island, Pulo Babi INDIA
• Andhra Pradesh, Rishikonda INDIA
• West Bengal, Hugli River INDIA
• Tamil Nadu, Kanniyakumari INDIA
• Maharashtra, Thane-Mumbai Bay (Lat: 18.91) (Long: 72.83) INDIA (Record: 06/2000-09/2001) (Depth: -15 mts)

Literature Source(s)
  • Ramakrishna; Sarkar, J and Talukdar, S (2003) Marine invertebrates of Digha coast and some recomendations on their conservation Records of the Zoological Survey of India ZSI, Kolkata 101(3-4) 1 Available at - NCL, Pune
  • Hussain, SM Brief report on biodiversity in the coastal areas of Pakistan p 113
  • Integrated Taxonomic Information System (ITIS) Available at -
  • Fernando, SA (2006) Monograph on Indian Barnacles Ocean science and technology Cell, Kochi 9-199 Available at - NIO, Goa
  • Society for the Management of European Biodiversity Data (2009) World Register of Marine Species (WoRMS) Available at -
  • Hewitt, CL; Martin, RB; Sliwa, C; McEnnulty, FR; Murphy, NE; Jones, T and Cooper, S (Eds.) (2002) National Introduced Marine Pest Information System Available at -
  • Swami, BS and Udhayakumar, M (2010) Seasonal influence on settlement, distribution and diversity of fouling organisms at Mumbai harbour Indian Journal of Marine Sciences National Institute of Science Communication And Information Resources, CSIR, New Delhi, India 39(1) 57-67 Available at - NIO,Goa

Page last updated on:2011-01-25

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