cnidaira

Great Star Coral (Montastraea cavernosa)

…a species of colonial brain coral (Faviidae) which occurs in shallow/moderate Caribbean waters. Great star coral colonies can grow quite large with colonies forming massive “boulders” over 5 feet (1.5 m) wide, with individual polyps the size of human thumbs! Like other corals great star corals are carnivorous, with polyps feeding on passing zooplankton. 

Classification

Animalia-Cnidaria-Anthozoa-Scleractinia-Faviidae-Montastraea-M. cavernosa

Image: NOAA

The blue coral, Heliopora coerulea, is named for its distinctive, permanently blue skeleton, which is covered by greenish-grey or blue polyps. This species is the only living octocoral known to produce a massive hard skeleton similar to that of stony corals to which it is only remotely related.

More about this species: http://eol.org/pages/1006937/details

Image by Lovell and Libby Langstroth via CalPhotos

Jelly ID

Hey Pax my friend Nikki encountered this thing and said that it was following her around in the water and has no idea what it is. Think you could shed some light on it for her?

Paxon:

This looks like the underside of a Blue Button Jelly (Porpita porpita). Its not a dangerous jelly, though its sting can cause some minor skin irritation. Show her this, and see what she thinks.

http://en.wikipedia.org/wiki/Porpita_porpita

http://eol.org/pages/1015954/overview

http://marinebio.org/species.asp?id=2267

Velella is a genus of free-floating hydrozoans that lives on the surface of the open ocean, worldwide, and is commonly known by the names by-the-wind sailor, purple sail, little sail, or simply Velella. The most common, and perhaps the only species encountered is Velella velella.

These small cnidarians are part of a specialised ocean surface community that also includes the cnidarian siphonophore known as the Portuguese Man o’ War, as well as some specialized predatory gastropod mollusks, including nudibranchs (sea slugs) in the genus Glaucus and purple snails in the genus Janthina, all of which eat Velella

(read more: Wikipedia)   (photo: Jymm)