Echinodermata Phylum Echinodermata Derived from the Greek meaning Spiny Skinned Ancient animal group that evolved over 600 ma Six classes living today Sea stars (Asteroidea) Sea urchins (Echinoidea) Sea cucumbers (Holothuroidea) Featherstars (Crinoidea) Brittlestars (Ophiuroidea) Sea daisies (Concentricycloidea)
Echinodermata Characterised by 3 major features 1. Radial symmetry body usually divided into 5 equal parts arround a central axis 2. An internal skeleton made up of calcite plates which usually bear spines 3. An internal water-vascular system most echinoderms move through extensions of the water-vascular system called tube-feet/podia
Sea Stars (Asteroidea) Crown of Thorns (Acanthaster Planci) Voracious coral predator Up to 21 spine-covered arms Arms are short relative to body disk Spines are toxic and can cause painful wounds Colour variable, often redish shades
Sea Stars (Asteroidea) Cushion Star (Culcita sp.) Inflated, cushion-like body Pentagon shaped Indistinct arms Variety of paterns and colours
Sea Stars (Asteroidea) Other Sea Stars
Sea Urchins (Echinoidea) Circular body outline with no projecting arms Generally nocturnal often hidden under rocks or in crevaces during daylight hours Some species cluster by day Predators triggerfish and pufferfish Mouth located on underside indicative of their bottom feeding lifestyle Most are algeal feeders, others feed on a variety of encrusting organisms (sponges, bryozoans, ascidians) Anal opening on upper surface some have a cloaca protruding from the anus Shells fairly hollow, very little space taken up by internal organs
Sea Urchins (Echinoidea) Short Spine Urchin (Echinothrix sp.) Body 9 cm, spines 7 cm Commonly totally black Juveniles can be banded Spines noticably shorter than the Long Spine Urchin (Diadema sp.) General rule: spine length approx equal to body width Nocturnal, so often hidden Sometimes forms aggregations in the open
Sea Urchins (Echinoidea) Long Spine Urchin (Diadema sp.) Commonly totally black but colour can vary Long spines Body 7 cm, spines 30 cm General rule: spine length is longer than body width Some species have electric blue lines radiating from the centre Often in congregations
Sea Urchins (Echinoidea) Mathae s Urchin (Echinometra sp.) Body 9 cm, spines 4 cm Colour variable grey, purple, pink, beige White circle on body around the base of each spine Spines slightly thicker than the long and short spine urchins Spines tapered with pointed ends Rock borer Often hidden by day, more exposed at night
Sea Urchins (Echinoidea) Pencil Urchin Variable colours Very thick spines Blunt spines Spines may be banded or solid and can display significant algeal growth Secretive and hidden durring the day Body 10 cm, spines 12 cm More active at night
Sea Urchins (Echinoidea) Flower Urchin (Toxopneustes sp.) Toxic! Is known to have caused the death of 3 divers Pink flower-like pedicillariae among spines Commonly seen on areas of sand or rubble Body 15 cm, spines 3 cm Usually covered in small fragments of rubble which can make them hard to see
Sea Urchins (Echinoidea) Cake Urchin Body 15 cm, spines 2.5 cm Many colour variations 10 bands of tiny pedicellariae and 10 bands of short spines radiate between mouth and anus Bands give it a segmented appearance...hence it s name Often covered in rubble and/or seagrass fragments
Molluscs Phylum Mollusca Includes marine snails and seashells Large diverse group containing over 100000 species About half are marine species others are pelagic, terrestrial or freshwater species Taken from the Latin mollis meaning soft Their bodies are soft and contain blood and a gut Some have an external calcareous shell Several classes of diverse appearance within the Mollusca Phylum GVI monitors species from the classes Gastropoda and Bivalvia
Gastropods Drupella sp. Relatively small shell 5 spiral rows of nodules on body whorl Nodules also present on spire giving it an overall knobbly appearance Coral predator Feed on the polyps of hard corals 4 cm
Bivalves Giant Clam (Tridacna sp.) 40 cm Large heavy shells Radiating ridges and scalloped edges Most attach to coral substrates Colourful mantle tissue often exposed variable colour Filter feeders, but also consume the symbiotic algae contained in their mantle tissue
Bivalves Oyster Some species are easily confused with giant clams (similar size and shape) However, oysters have zigzig or straight apertures, giant clams have wavey apertures