Octopus

Description:

It is very hard to see what is going on here so there is a need for a small explanation - this is a daytime hiding place, or burrow, of an octopus. The animal is hiding under a bigger rock, and it moved and piled smaller stones around the entrance. Through these smaller stones, we can see a part of a tentacle and one large sucker - in order to compare the size, when I saw it, my impression was the sucker could cover my fingernail. The second pic, although blurred since it is the same pic but cropped more aggressively, allows maybe a better peak to this.

Habitat:

Seen at about 8-9 m of depth, on a rock-sand bottom platform not far away from shores, near Dubrovnik.

Notes:

For me, it is difficult to specify the species from what I've seen - my best guess would go toward Common Octopus (Octopus vulgaris) - it is a common species in Adriatic, and is often seen or reported on rocky shores around Dubrovnik. But, there is another common species of octopus around, the Musky Octopus (Eledone moschata; locally known as Muzgavac). The later prefers sandy bottoms, and has shorter tentacles, and only one row of suckers on them. Unfortunately, from what I saw and photographed, I can't be completely sure about the species.