Chthalamus fissus has three representative morphological types. Its most common morph is represented by an upright, dorsal, oval operculum. The second morph type is not as common in which the entire outer shell is bent and the operculum opens to one side. Unlike other other barnacle species, it also exhibits a rare third morphology in which the operculum is dorsal and extremely narrow 'slit-like'.
It is suggested that the two uncommon morphological types, bent and narrow operculum, may represent a defensive strategy. In which, the narrow and bent morphs are better defended from attack by its main predator, Mexacanthina lugubris lugubris. To feed, the predatory snail jams its shell spin into the barnacle operculum. A narrower or bent operculum may be more resistant to M. lugubris lugubris's penetrating shell spine.
It is suggested that juvenile C. fissus have the opportunity to develop either a narrow or bent morph before they become large enough to be considered suitable prey. It is unknown what the energetic costs are behind developing either defensive morph type. There are many hypothetical advantages and disadvantages behind developing either morph. The narrow morphology is suggested to be an intermediate between the desire to avoid predation and the energetic cost related with developing the bent morphology. The bent morph may be best at avoiding predation but may also be too energetically costly and may impair C. fissus's feeding ability.
Molecular Biology and Genetics
Barcode data: Chthamalus fissus
Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.
See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Chthamalus fissus
Public Records: 7
Specimens with Barcodes: 7
Species With Barcodes: 1
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