Naked Science Forum

Life Sciences => Plant Sciences, Zoology & Evolution => Topic started by: EvaH on 16/11/2018 13:34:43

Title: How can a heron swallow a fish whole without injury?
Post by: EvaH on 16/11/2018 13:34:43
Kyle wants to know:

Visiting a beach at the ocean, I recently saw a Great Blue Heron dive and catch quite a spiky/large (and colorful! I think it was called a sculpin) fish crosswise in it's bill. It appeared that potential meal was fighting hard to prevent it from becoming the determined bird's dinner. This fish had to be a little over a foot in length, quite thick, and plenty of spiky fins! Still, within about a minute the heron had it face-first and then gulped the thing thrashing the whole way down itís long neck!!

It was a bit gruesome to watch the  climax... I thought it was finally over, but once in the gullet/stomach you could see the fish strongly kicking much to the discomfort (it appeared) to the bird!

We didn't hang around for much longer. I wonder if that was the end for the fish or if the heron had won its meal?

Still, wouldnít the sculpin stand any slim chance of escaping or even damaging (thrashing, sharp fins, biting, etc.) the bird's insides if eaten in that condition?? I imagine the herons elastic/stretchy insides could possibly work against itself, giving the fish a chance to turn around? It must be a some meal for the heron and I wonder if it handles it bones and all as well?! Thanks!

What do you think?
Title: Re: How can a heron swallow a fish whole without injury?
Post by: Colin2B on 18/11/2018 15:16:23
Firstly the heron, as you noticed, rotates the fish to swallow head first this means the spiky dorsal and pectoral fins will flatten against the body so it will go down smoothly.
Secondly, we tend to think of bird stomach as being like the human sack shape, but in fact it is a tube shape (proventriculus) between the crop and gizzard. Although the fish can thrash around the narrow tube holds it in one direction, it canít turn. The proventriculus also secretes gastric acid to start the digestion process.