How abalone fall in love: tracking down the pheromones involved in sex attraction


A project undertaken at The School of Biological Sciences, The University of Queensland, and supervised by Dr Scott Cummins

Pheromones are chemicals used to communicate between animals of the same species, and are thought to be used by most marine animals. With limited vision, the abalone primarily sense their world chemically, which plays an important role in larval settlement, aggregation (Figure 1), recognition and synchronous gamete spawning. Little do people know that abalone perform their own version of getting together on the ocean reefs, made possible by a combination of the moons lunar cycle and powerful chemical signals, called pheromones.  As a result, they release millions of gametes at precisely the same time, in the hope of creating thousands of offspring. Aggregative behavior is essential to increase the chances of successful gamete fertilization. Queensland’s coastline (Figure 2) offers the ideal, safe breeding ground for these animals, where they can secretly convey these signals. For abalone, environment cues are detected by two main olfactory appendages, the cephalic and epipodial tentacles (Figure 3).

Prior to this study, there had been no detailed investigation into pheromone substances, both in their precise biochemical nature or pheromonal function. In this study, we are investigating the presence of pheromone-like substances from mucus secretions of the tropical abalone Haliotis asinina using bioassay, biochemical and genetic tools. Mucus is widely used as a source of information amongst snails, such as locating mating partners and to discriminate between conspecific and heterospecific individuals. To investigate the active biomolecules necessary for abalone attraction and aggregation, we aim to:

  1. Characterise the peptides within male and female abalone mucus by analytical biochemical  (Figure 4) and molecular genetic tools.
  2. Assay candidate pheromones using designed behavioural experiments.

The overall outcome of this work will contribute to fundamental knowledge of how pheromones can so efficiently relay essential information in the harsh aquatic environment, a biological practice that has proven successful for millions of years. Australia has the one of the richest diversity of molluscan species in the world and is an excellent geographic locale to further explore the occurrence and diversity of marine chemical communication.


Collaborators

Bernard Degnan (The University of Queensland), Chitraporn Kuanpradit (Mahidol University)

 

Figure 1. Abalone aggregations increase the chances of gamete fertilization success.

Figure 2. Heron Island reef is the perfect breeding ground for abalone.

Figure 3. Abalone have cephalic tentacles and epipodia over their body which act as a finely tuned nose.

Figure 4. High performance liquid chromatography isolation of mucus biomolecules.