Hi Angelo,

Sexual dimorphism in Acanthaster planci does not exist, so using morphological features to separate the sexes in crown-of-thorns starfish in situ is not possible; at least to my knowledge. However, it may be possible to separate the sexes using the technique that Keesing et al (1997) used in their laboratory experiments (see attached paper). However, their approach (i.e., taking a biopsy with a large bore syringe and looking at its content) will only work during the crown-of-thorns breeding/spawning season. If doing the biopsy in the field is not possible then perhaps an in-situ injection of specimens with 1-methyl-adenine to induce spawning may be an option. After injection the males should spawn within in 5-10 minutes and females in about 30 min. Spawning individuals can then be separated into males and females. This is a laborious and time consuming approach as well, and will only work during the breeding/spawning season.

Thank you for your kind response, Prof Tomas (Tom) Tomascik . The reason why I am looking for a means to identify the sex in situ is that the site for field collection is roughly 6-8 hours from our lab. Can you suggest any means how to transport 10-15 species of large A. planci? Thank you very much

Angelo,

Is your lab reachable by boat/ship from the location sites, or do you need to transport over-land as well. If you can transport the specimen by boat then transporting the COTS is relatively easy just place them in covered plastic bins with running seawater using small water pumps.

Transport by truck/car will be more difficult, but as long as you can somehow maintain the temperature and oxygen levels in the plastic bins you should be OK. You can use basic aquarium battery powered air pumps to maintain the oxygen levels in the bins. You can use cheap air pumps that can be bought either in pet shops or on Amazon.com; here is one example: https://www.youtube.com/watch?v=xI1H4rQzoaI

These small air pumps will aerate the water in the bins to maintain oxygen levels. You should also have a number of spare buckets full of seawater only so that you can do partial water exchanges during your trip.; let's say every 1/2 hour. Maintaining the temperature will be important and you can do this by lining the outside of the plastic bins with insulating material like styrofoam. In fact you could check in your local shops to see if they sell large cheap styrofoam coolers and use them instead of the plastic bins. Something like this

http://www.dryicepacks.com/scripts/prodView.asp?idproduct=42

should work to keep the temperatures cool. You can buy additional coolers for your spare seawater to be used for water exchange as well.

Hope this will give you some ideas what's possible.

Tomas

Thank you very much for this very detailed answer, Prof Tomas (Tom) Tomascik ! I really appreciate your technical expertise in this subject.

I've always had luck using a cooler with pump/oxygen stones and small freezer blocks (the ones used in lunch bags). We lost specimens if the water became too warm but never when it was cooled down and they were in transport for a couple of hours (west coast). They were sluggish when first placed into the tank but warmed up after a few minutes.