Beachcombing

Maia McGuire, PhDSea Grant Extension Agent

Beach zones

• Dune• Berm/backshore

– Wrack line/strand line

• Foreshore– Swash zone

• Nearshore/breaker zone• Offshore

High tide I I

Low tide

Subtidal

Backshore

• Ghost crabs

Wrack line

• Often created during storm events• Seaweed, debris• Amphipods (beach hoppers)• Sea beans, seashells• Other “treasures”

• www.seabean.com• Any of a number of seeds that are

adapted to germinate even after spending a period of time floating in water

• Mostly from tropical plants, many from vines

Sea beansSea beans

Seashells

• Phylum Mollusca• Class Gastropoda• Classes Monoplacophora,

Polyplacophora (primitive)• Class Bivalvia• Class Scaphopoda (tusk

shells)• Class Cephalopoda

Mollusks

• Generally have muscular foot, calcareous shell secreted by the mantle, feeding organ called radula

• Larvae are often planktonic veligers

www.pbs.org

www.seaslugforum.net

Gastropods

• “Snails”• Head with eyes on tentacles• Usually relatively active/mobile• Usually coiled shell into which

animal can retreat• Includes sea slugs• Grazers or predators

Moon snail (“shark’s eye”) Operculum

(“trap door”)

Egg collar

Bivalves

• Shell has 2 (hinged) valves• Adapted to burrow in soft

sediments• Most are filter-feeders• May be attached (cement, byssal

threads), burrowers/borers or free swimming

Cephalopods

• Octopus, Squid, Cuttlefish, Nautilus, Spirula

www.manandmollusc.net

Other “treasures”

Crab shells

• Moult or dead? (i.e. will it stink when I get it home?)

• Male or female?

Polychaete worm

casings/tubes

Sea anemones

Sand dollar/keyhole urchin

Purple sea urchin

Sea Stars

Astropecten articulatusMargined Sea StarCommon Sea Star

Asterias forbesi?

Sea cucumbers

Mermaid’s purse (egg case of clearnose skate)

Stingray barb

Jellyfish• Portuguese man-o-war

– Don’t touch!– Associated companions—”By-the-wind

sailor”, “blue buttons”, purple sea snail, man-o-war slug, man-o-war fish

www.enature.com

www.amonline.net.au

Cannonball jellyfish

www.jaxshells.org

Moon jellyfish

www.jaxshells.org

Swash zone

Live critters

• Coquinas• Augers• Mole crabs

www.jaxshells.com

Sharks’ teeth

Marine Debris

• PLASTICS!!!

Synthetic Sea

Sand

To see a world in a grain of sandand a heaven in a wildflower,

hold infinity in the palm of your hand

and eternity in an hour.William Blake

Where does sand come from?

• Erosion of rocks (on land)– NE Florida sand is silica-based; comes

mostly from mountains of NC

• Formed by marine plants/animals– Shells, sea urchins, etc.– Corals– Calcareous algae (macro- and

microscopic)

Sand colors

http://www.paccd.cc.ca.us/instadmn/physcidv/geol_dp/dndougla/SAND/SANDHP.htm