Hemisquilla californiensis

Gonodactylus

Premium Member
I got a couple of male Hemisquilla californiensis from southern California. They are difficult to keep due to the need for cool water (15C) and the fact that they usually develop fungal infections within a few months in the lab, but they sure have nice colors.

Roy

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Pretty dull in the lab. They just don't adapt very well to captivity and spend most of their time in burrows. However, there behavior in the field is another matter. The forage over long distances returning prey to their burrow. I once followed a male over 50 yards trying to get some decent video of him foraging. I suddenly realized that he was taking me in a large semi-circle. I was between him and his home. Once he managed to circle around so that I was no longer in the way, he made a beeline for the burrow. I swam a fast as I could, but there was no way I could keep up with him.

The reason we work on Hemisquilla is their commicnation systems. The red patches on the carapace (only in males) are strongly polarized and the animals produce a low frequency growl by vibrating their carapace.

Roy
 
It's interesting to hear the behaviour of the species differs greatly in the wild. Do any other species of Stomatopod communicate with vibration?
 
Dr Roy, I just returned from Integrative Biophysics summer school in Germany on Biophotonics. It is a very interesting frontier discipline that is barely studied here in the US. They look at living systems under complete darkness and observe the ultraweak photon emission given off by the cell or organism. They use either PMT if looking for coherence in the signal (indicating the capacity for communication) or can use a CCD camera for spatial detection and imaging of the emissions. Two types of methods are used: Delayed luminescence where the specimen has a broad spectrum or monochromatic light shined on it for a variable time (up to the saturation point) and then the decay emission in measured. The other is spontaneous emission where the specimen is kept in the dark for 30-45 minutes such that any delayed luminescence fades off, and then the light generated purely by the organism (or food, fruit, algae, bacteria, tumor, skin, etc) is measured and analyzed with statistics. With these methods, quick detection of cancer cells, spoiled foods, bacteria growth, cellular communication, seed germination capacity, mode coupling, water purifcation detection, quality control, etc, etc with new possibilities arising as the technology becomes more "wide-known".
This new biophysics was originally discovered in the 30's but was primarily disregarded in the west, but the Russians and Germans continued research to this day and have made some astounding discoveries. The summer school I went to is the only one in the world, and I was one of 3 Americans of the 28 international students, along with 18 Prof's/Scientists/researchers presenting...
It would be interesting to try and record the delayed luminescence from the polarized areas on the stomatopods.... only issue being it has to be in complete darkness...
any ideas??
 
There is only one other species that we know produces a low frequency sound by vibrating the carapace and that is Lysiosquillina maculata. We don't know what the sound is used for. For that matter, we don't even know that they can "hear" it since they do not have a structure that would be termed an "ear". In Hemisquilla, they "growl" when something enters the burrow. There are also reports that suggest that the sound may play a role in attracting a mate. One of these days I'm going to set up some hydrophones and infra-red video near burrows and see if I can figure this out. For now all I can say is that they vibrate their carapace when disturbed.

The only other signal that I'm aware of that involves sound is a study that I did many years ago that showed that if a cavity resident successfully defended its cavity, it would often strike the substrate as the intruder fled. I viewed this as a "victory" display that punctuated the defense.

Roy
 
Where were these collected? It would probably be best not to give a specific location, but just a general area? I'm curious because I'm from So Cal.
 
Hemisquilla californiensis can be found from Santa Barbara to Panama. I usually collect animals from the lee side of Catalina, but any open muddy sandy slope at 40-80 feet usually has Hemisquilla. They are most likely to occur in protected bays or in deeper water. A word of caution. These are large, powerful stomatopods that can do considerable damage to a divers hand. Use nets and gloves when collecting them.

Roy
 
<a href=showthread.php?s=&postid=8001541#post8001541 target=_blank>Originally posted</a> by Gonodactylus
Hemisquilla californiensis can be found from Santa Barbara to Panama. I usually collect animals from the lee side of Catalina, but any open muddy sandy slope at 40-80 feet usually has Hemisquilla. They are most likely to occur in protected bays or in deeper water. A word of caution. These are large, powerful stomatopods that can do considerable damage to a divers hand. Use nets and gloves when collecting them.

Roy

Pretty interesting that these guys are living in my local waters. I've heard stories of divers getting messed up by large stomatopods... I'll just stay away all together. Thanks for the info!
 
H.californiensis almost seems to have a blade like hitting surface/hill on their dactyl? Are their weaponary different from the usual smashers that exhibit a rounded hill at the hitting surface of the club?
 
i was going to ask the same question as wenwu did, im horrible at defenitions and stuff like that but i think when he says primative smasher it is less evolved than a reagular smasher, but more evolved than a spearer. just a guess
 
I'm usually more careful with my choice of words. We are not even sure if the first stomatopods were spearers, smashers or had non-specialized dactyl like Hemisquilla. Molecular data from my lab suggest that squilloids are closer to the root of the stomatopod tree, but many other researchers think Gonodactyloids may be more basal. It is going to take a lot more work to sort this one out.

The dactyl of Hemisquilla is very similar to some early stomatopods such as Pseudosculda, but that is probably just convergence.

Currently, Hemisquilla is placed withing the Gonodactyloidea, but several aspects of its morphology suggest that it may a very old lineage not closely related to other mondern stomatopods.

Roy
 
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