Who you callin’ a lyre?

My animal physiology (Biol 310) class studied osmoregulation in lyre crabs Hyas lyratus (last semester… I know I’m a little late talking about this). We (my husband and I) measured osmotic concentration in the hemolymph of lyre crabs at “100%” seawater (southeast Alaska experiences TONS of rain, so the water here is not really 100%) then put them in either ~60% and ~80% seawater for 48 hours. Then we (the class and I) measured the lyre crabs’ new osmotic concentrations and compared them to the environmental osmolarity.

Hyas lyratus, with a face only a mother could love

(aw, I love her too!)

our high-tech set-up:

60% seawater on the left, 80% seawater on the right

Any point that falls on the conformer line (the dashed y=x line) represents an animal that keeps their internal osmotic concentration the same as the external environment. A point above the line represents an animal that is regulating its osmolarity.

Just with our little experiment, at 100% and 80% seawater, the lyre crabs appeared to be osmoconformers. Once they were in 60% seawater they began to try to regulate their osmolarity with the hopes for survival. (One female did die in the 60% seawater treatment, but we didn’t have any other mortalities and all crabs were returned to 100% seawater in the wet lab after the experiment).

Lyre crabs just aren’t the regulators like other crabs, for example the green crab Carcinus maenas and Chinese mitten crab Ericheir sinensis. These guys are way better at regulating their internal osmotic pressures: C. maenas has a survival limit at about 33% seawater, and E. sinensis can even survive in fresh water, although they need to be in saltwater to reproduce. I guess that’s part of what makes them such great invasive species (and maybe why we’re NOT seeing lyre crabs all up in everyone’s business).
 

invasive crabs... what are you gonna do, eh?

(Exo)skeleton Costumes

Crabs have all the luck: they're already dressed for Halloween.

Scotty: "Um, I can see your skeleton."

But why are vertebrate skeletons so intriguing during Halloween? Maybe because they protect so much, but are hidden. Here we have vertebrates with their spinal column protecting their spinal cord:

Charlie Brown's skeleton: see his spine?

Blossom's short, and so is her spine.

This was just weird.

And there are so many more like this! Look them up here!

Crustaceans have an exoskeleton, meaning they don't have a spine to protect their nervous system, just their carapace. When you dissect a crab or lobster you can see their ventral nervous system easily (once you remove their organs and such):

the nervous system of a Chionoecetes bairdi female:

the clear/white cords are nerves going to each leg

a clearer drawing, from this book

Homarus americanus ventral nerve cord and ganglia (also clear/white)

are more spread out with their longer carapace (dissected during Biol 310 lab)

If anything, crab skeletons are way cooler (and a bit more creepy). Either way, have a Happy Halloween!

really?

Happy Belated Alaska Day!

What did you do to celebrate Alaska Day? I staged chromatophores on shrimp with the Biology 310 lab I'm TA-ing! Exciting, right?

the carapace of a shrimp (Pendalus sp.) with its chromatophores (the orange starbursts)

Chromatophores are pigment-containing cells that generate shell color for crustaceans. Some crustaceans can change color to match their backgrounds (cephalopods are also awesome at this!). And, like all things interesting (to me), chromatophores are under hormonal control!

To stage the chromatophores, the students looked at shrimp under dissecting scopes and determined how dispersed the pigments were. A dot is considered stage 1, but the more branching and dispersed the chromatophore, the greater its stage (with 5 being the most dispersed).

more pretty chromatophores!  I'd stage these as 3's and 4's

Pineapples!!!! Really, chromatophore pineapples!!!!

These were from Kevin's physiology project last year.

I'm not sure how I'd stage these, but probably stage AWESOME!

Not specifically Alaskan, but fun nonetheless. Still, let's take this time to appreciate some of the many wonderful Alaskan crabs:



Southeast Alaska intertidal crabs!

Dungeness crab, hermit crab,

mud crab (the purple thing), and red king crab



Happy Alaska Day!