Hemisquilla Californiensis

[Msby12]

well, last saturday, i went fishing with some buddies on one of the piers in redondo beach,

we were talking about weird things we had seen, and i said that a guy next to me had caught a mantis shrimp ( saying hemisquilla californiensis would've sounded weird), so i kinda described it, and then, Lo and Behold!!! the person next to us on the pier reels up one of them! :eek2:

a department of fish and game guy told the fisherman to throw it back because he said it had eggs, but i thought Stomatopods carry their eggs in between their datcyls?

also, i asked the DFG guy why that particular shrimp looks like a spearer, cuz i thought they were smashers, and he told me that the species can be both! now i'm confused!!!

PS: I looked at a picture of one, and i can see the spearing part that can be extended, but the heel looks like it wouldn't be as effective at smashing than it would be at spearing!

 

[mattyice]

Hemisquilla Californiensis is a primitive smasher, if you look at pictures it doesnt have a the same developed raptorial heel as other smashers, the thing is that even though it doesnt look like it but all smashing stomatopods have that third raptorial appendage that can unfold like the spearing types but i dont think is as effective or effective at all compared to the spearing stomatopods

and yes stomatopods carry all eggs with their maxillipeds, maybe he meant that she was about to lay some eggs and he could tell.

my question is how big was it?

 

[Thurge]

Having been stuck by one of my mantis, I can confirm that they are quite effective at using the sticker part of there smashing club.

 

[mattyice]

are you sure it was the third part and not that it just struck you hard enough to break skin

 

[justinl]

I read somewhere that smashers do indeed extend the third segment to spear soft flesh and reserve the heel for hardstuff like shell and rock. It makes sense right? It would cost less in terms of effort and energy to use a sharp spear and longer reach when possible. Especially because "soft" things usually include fish which are relatively fast.
so maybe the spear/smasher classification is just dividing them into what they mainly do?

 

[DanInSD]

I can tell you from personal experience that H.c. uses its third segment as a slicing implement. We had one for a brief time in our high school classroom, and saw it split things like shrimp in half with the "spear". The thing is like a razor blade.

 

[rwhhunt]

My peacock used to disengage her dactyl revealing the fearsome razor sharp serated blade on the backside... I only saw her use it once when she disembowled a fish in front of me....

 

[Msby12]

yeah, i know that even smashers have that sharp endpoint, i learned that about a few months ago when my peacock took a few swipes at a damsel and after much confusion, i checked online to roy's list.

oh yah, mattyice, it was about 9-12 inches long!!! the guy who caught it had some really big tongs to hold it!

 

[mattyice]

lol im sure he would of, and the reason i didnt think that they use it is because when my peacock killed damsels he did it with the force of his smasher

 

[Gonodactylus]

I don't understand the reference to a third appendage. All stomatopods have one pair of raptorial appendages. The striking appendage of a stomatopod is the 2cd thoracopod, also called the 2cd maxilliped or the raptorial appendage. As you work your way out from the proximal connection of the appendage to the distal last segment, it is the coxis, basis, ischium, merus (largest segment that contains the muscles that power the strike), carpus (small knuckle that functions as the trigger), propodus (segment that swings out) and the dactylus (the terminal segment that is either a simple blade, barbed, or that has an inflated heel that forms a hammer). All stomaotpods can strike with the dactylus - propodus joint open or closed. How the strike is made depends on the target. Most smashers strike armored prey with a closed dactylus. They strike soft-bodied prey and predators with an open dactyl impaling it. There is considerable variation on the dactyl morphology of smashers. Hemisquilla has a simple, blunt blade with no spines on the inner surface. The strike is fast and powerful and can easily cut a shrimp in half, but they rarely open the dactyl and stab (although I have had it happen to me). They also strike armored prey such as abalone with a closed dactyl. Also, if you have seen some of Howard Hall's video with a Hemisquilla attacking an octopus, the strike was closed. About the only thing which seems to reliably cause them to stab with an open dactyl is if they are grabbed and held by a hand or mouth. Then they stab with both the dactyl and the uropod spines.

Spearers have a varied morphology. WIth from 3 to over 27 spines set on the inner edge of the dactyl, they typically impale prey. However, the spines are often barbed and they do not usually stab predators. Rather they strike with a closed dactyl. I think the reason is that the barbed spines can become stuck in an opponent and the long appendage easily torn off.

Most smashers have just a single spine as the tip of the dactyl, but the Odontodactylids have from two to several short spines on the inner margin.

We really do not know which type of dactyl is primitive. The oldest known fossils have a dactyl that is not armed with spines and does not have an enlarged heel. The Sculda, another old group of Stomatopods have never been found with an intact raptorial appendage so we don't even know if they had one. The Pseudosculda had a simple sickle shaped blade. By 100 million years ago, all of the major superfamilies had evolved. It appears that smashing and spearing has evolved back and forth several times.

For various reasons besides the dactyl I think Hemisquilla is an old, unique lineage. We are waiting for molecular data to confirm that.

Roy

 

[Msby12]

well dr. roy, since we're not experts, (like you are ) we kinda use less specific terms.... since the dactyl has two joints (i think) i guess one could say there are three parts

for example, the sharp barb would be the hand, the next part would be the forearm, and the last part.... uhm i think that's just called the arm. blah, kind of a bad explanation of what we're trying to say....

now if you can fold your arm like a stomatopod, post pics!

 

[Thurge]

I am quite sure the little bastard stuck me. I was feeding him (by hand, a treatment he doesn't get anymore) and in one swift movement he stuck me and grabbed the krill I was trying to give him. I have been smacked by this particular mantis on several other occasions when cleaning algae out of the tank, so I know what that is like also. This time I blead like the proverbial stuck pig, and had TWO holes in the tip of my finger, one entry and one exit wound. Got pictuers on my camera, I just need to do some maintanence on my home PC before I DL them from the camera.