Echinoderms and elasmobranchs

Organismal organization may have not been the best idea...here are some small things and big things.

Nerd notes: echinoderms are invertebrates with five-part radial symmetry, and include starfish, sea urchins, and sea cucumbers. Invertebrates in Palau are poorly studied and many are undescribed--I'll talk more about an invertebrate biodiversity study we're working on in an upcoming post. The species names I've put here are my best efforts, but classifications may have changed or may not be known.

Elasmobranchs are cartilage-skeletoned sharks and rays, which really belong with the fishes post.

Giant sea cucumber or amberfish, Thelenota anax; Blue Corner

Brittle star, Ophiotrix spp.; New Drop Off

Crinoid, Siaes Corner. The best I can identify this is to the class Crinoidea! 

Possibly Hefferan's starfish, Celerina heffernani; Sandbar

Big-plated sea star, Choriaster granulatus; Ulong Channel

Gray reef shark, Carcharhinus amblyrhynchos; Ulong Channel

Manta ray, Manta birostris; German Channel

German Channel's topography stirs up plankton-rich waters, and mantas frequent certain feeding stations where divers can sit and watch as the rays turn in lazy laps, seemingly unperturbed by the onlookers.  

Mantas use their cephalic fins at the front of the head to funnel plankton past their gills. When they aren't feeding, they roll these fins up for a more streamlined swimming profile. 

Another gray reef shark at a cleaning station at Blue Corner