Cyprid settlement

For Balanus amphitrite, a waterborne settlement inducer that is more active than the surface-associated settlement factors has been extracted from seawater conditioned with adult barnacles.53 The cyprid settlement responses could be stimulated by peptides bearing C-terminal arginine or lysine residues.54 102 Interestingly, the same barnacle settlement-inducing peptides attract a variety of barnacle predators such as oyster drills.53103... 

Elboume PD (2008) Ecological role of an adult-derived, waterborne cue in cyprid settlement in the barnacle Balanus amphitrite Darwin. PhD thesis, Newcastle University, pp 327... 

The bromotyramine derivatives ceratinamide A (136) and psammaplysin A (137) from the sponge Pseudoceratina purpurea inhibit the settlement and metamorphosis of cyprid larvae of the barnacle Balanus amphitrite (ED50 0.10 and 0.27 (Jg/ml). Interestingly, psammaplysin A induces larval metamorphosis of the ascidian Halocynthia roretzi (ED 0o 1.2 (Jg/ml) [74]. 

Yule, A.B. and Walker, G., Settlement of Balanus balanoides the effect of cyprid antennular secretion, J. Mar. Biol. Assoc. UK, 65, 707, 1985. 

Settlement of barnacles, especially the now cosmopolitan species Balanus amphitrite, has received extensive attention. Rittschof53 pioneered the investigation of the role of specific soluble peptides released as metabolites into seawater by adult barnacles as larval-settlement stimuli for invertebrate larvae, especially those of barnacles. Cyprid larvae of B. amphitrite are powerfully stimulated to settle to surfaces and walk upon them by the presence of very low concentrations of dissolved peptides with a C-terminal arginine or lysine residue.53-54 However, there are reports of attachment and metamorphosis of cyprids of B. amphitrite, in the absence of a soluble peptide cue,... 

The role of biofilm bacteria in barnacle settlement has been a topic of considerable investigation and discussion (see Sections II and III.C above). Despite numerous studies finding positive associations between biofilms and the settlement of barnacle cyprid larvae, Roberts et al.,198 using shortterm field tests of treated surfaces, found, Although bacterial films can have dramatic effects on settlement of barnacles and bryozoans...they are not essential for colonization by barnacles, bryo-zoans or hydroids. ... 

Larman, V. N. and Gabbott, P. A., Settlement of cyprid larvae of balaunus Balanoides and Elminus modestus induced by extracts of adult barnacles and other marine animals, J. Mar. Biol. Assoc. U.K., 55, 183, 1975. 

Settlement. The fixation of the larvae of benthic animals does not take place randomly, but is sometimes guided by the presence of immerged substrata of organic substances deposited by adults previously fixed there. Thus, in the case of Balanus balanoides, the cyprid larvae attach themselves to surfaces where earlier barnacles have deposited a complex mixture of mucopolysaccharides and proteins associated to nucleic acids (Crisp, 1974). This mediator is not specific it is produced by several crustaceans smd has therefore received the name arthropodin. A similar phenomenon was described by Nott (1973) for the annelid Spirorbis spirorbis. 

Dreanno C, Kirby RR, Clare AS (2006b) Smelly feet are not always a bad thing the relationship between cyprid footprint protein and the barnacle settlement pheromone. Biol Lett 2 423 125... 

Abstract Many barnacle species are gregarious. This is an essential behavior for those species that can only reproduce by mating with a neighboring barnacle. Proximity of adult barnacles is achieved by gregarious settlement of the cypris larva. The chemical basis of this behavior was established 60 years ago, but attempts to characterize the cue to settlement met with limited success. This chapter presents evidence obtained in recent years that the cue is an a2-macroglobulin-like cuticular protein, detected by cyprids using a tactile chemical sense as they explore the substratum for a suitable settlement site. 

Fig. 22.1 Gregarious settlement of barnacle cypris larvae, (a) Cyprids approach the substratum, perhaps after encountering a waterborne cue released by adults (b) contact with substratum and onset of (c) searching behavior (d) cyprid contacts an adult conspecific and is stimulated to settle by a cuticular protein - the settlement-inducing protein complex (SIPC). The cyprid may return to the plankton at any stage of the sequence (b-d). Drawing by Jorge A. Varela Ramos...

Fig. 22.3 Choice assay used by Crisp to compare cyprid preferences for different substrata. Slate was used as a settlement substratum arranged in glass dishes set on a rotating table. The rotation mitigated against bias from external factors such as light. The air lines were used to impart a flow of seawater in the dishes...

B. amphitrite has become a model species for settlement studies owing to its economic importance, cosmopolitan distribution and relative ease of culture. How representative the findings of these studies are to other barnacle species remains to be fully established. Investigations on the SIPCs of different species are required to address fundamental questions concerning the role of the SIPC in barnacle evolution and the ability of cyprids to distinguish between barnacle species at settlement... 

Clare AS, Freet RK, McClary M (1994) On the antennular secretion of the cyprid of Balanus amphitrite, and its role as a settlement pheromone. J Mar Biol Ass UK 74 243-250... 

---