Halfway

We've come to the end of Pelagic Week #3 (hope you enjoyed it), and it's time for an octopus update!

Some of you will remember that we're documenting the development of some Red Octopus eggs in the lab (see post from 20 August 2013).  Here's a reminder of what they looked like on Day 36:

 

I took a few more pictures this week, and they've changed quite a bit.  Below is a new picture from Day 52.  At this time we think they're about halfway through their development (until hatching).  Compare the two pictures (above and below) to look for differences!

 

Here are a few changes we noticed:

• The eyes are now deep red rather than orange.

• The yolk is much smaller.

• The tentacles are much longer and suckers are now visible.

• They have chromatophores!

• The mantle, opposite the yolk, is much more developed.

To help visualize all of this, I've labeled these structures below.  This photo was taken on Day 55.

 

And because these little octopus embryos are so amazing, and I'm intrigued by the development and pattern of the chromatophores, I'm including one more close-up:

 

To review what chromatophores are and how they work, refer to the "Living paint" post on 2 February 2013.