Spinning embryos

From our lab at the RTC. Note the spinning embryos in the egg sack of Haminoea sp. (sorry about the shaky video)

Found the following on asnailoddysey.com about why the embryos spin: The gelatinous mass around the eggs of opisthobranchs acts to protect the eggs, but at the same time it does represent an “unstirred” barrier between the egg capsules and the external environment. Respiratory gases and other diffusible substances (e.g., ammonium) must diffuse sometimes several millimeters across the gelatinous material. Like all other opisthobranchs, late in development the embryos of Haminoea sp. begin to spin rapidly (50-100rpm) within their capsules. The authors calculate that spinning enhances gas diffusion by about 8% over what there would be if they were non-spinning. Hunter & Vogel 1986 J Exp Mar Biol Ecol 96: 303. Source: http://www.asnailsodyssey.com/LEARNABOUT/NUDIBRANCH/nudiHatc.php


Cirral movement of a Chthamalus barnacle

Chthamalus sp. from 11/3 lab.

I found an interesting paper about how barnacles move and use their cirri. I’m on the fence about whether this barnacle’s cirral movement would be considered #3 or #4 from the descriptions below.

(1) testing, in which the valves hardly open and the cirri are not protruded.

(2) pumping, in which strong rhythmic movements of the operculum occur, but the cirri are protruded only slightly, and not extended.

(3) normal beat, a development of pumping, but with the cirri fully extended and withdrawn in rhythm with the opercular movements.

(4) fast beat, with less opercular movement, but strong and fast rhythmic cirral movements.

(5) extension, in which the cirri are held outside the shell for varying periods without rhythmic movements.

Source: http://rstb.royalsocietypublishing.org/content/243/705/271

Acanthocephelan parasites

Hello, Bio 555 classmates. It is Tony here.

Had some hard time transferring images to computer but made it finally. Here are two pictures of the parasites I found from the Emerita analoga. One thing to apologize ahead, I forgot to mark down the magnification when I took these pictures under the dissection scope.

The ellipsoid part of the parasite is the main worm body part of this stage of the parasite. The transparent hollow part, aka proboscis, is the tubular mouth part of the parasite. According to the The LiMPETS website, Acanthocephelan parasites lacks of mouth and anus, as well as digestive tracks; therefore, this “mouth part” does not serve any feeding function. The way the parasite uses this mouth part is to anchor itself to the host’s gut and absorb nutrient through the worm body. According to Sarah, the parasite has hook like structures on the mouth part to accomplish the anchoring move.

*Picture one is the stage when the parasite has not yet shoot off its proboscis.

*Picture two is the stage when its proboscis has shot off.

*These parasites are from mole crab #626. Female. Carapace length: 33mm.


Picture 1
Picture 2



Who knew that mole crab appendages could be so fascinating? Not only are these uropods really cool looking with (note the iridescence and the fine feather-like setae), but I was reading that after Emerita analoga use their uropods to swim down to the surface of the sand that they continue to beat their uropods while… Continue reading Uropods