will be around until September. When they hatch their two mandibles are of equal length but by fl edgling, 4 weeks later, the lower mandible is already 1cm longer than the upper.Least terns (a threatened species) arrive on Marco in late April to breed and will have probably left again with new fl edglings by mid September. Their young can also fl y at four weeks of age. The least tern hovers until spotting prey and then plunges into the water without full submersion, to extract dinner. The lettered Olive shell has a strong foot that allows it to burrow easily through sand. They prey on coquina clams in the surf zone and scavenge when the opportunity arises.Horseshoe crabs are not in fact crustaceans but more closely related to spiders than crabs. Their molts are perfect replicas of the growing animal. Females take a decade to mature and live 20-40 years. The species is valuable in both pharmaceutical and bio-medical research.Atlantic giant cockles are over 5" in length and a strong muscular foot allows them to burrow into sand where they extend syphons above them into the water to fi lter for plankton and detritus. This species is over 65 million years old.The Lightning whelk acquired its name because the white shells of juveniles have chest-nut brown stripes with a zig-zag pattern reminiscent of lightning bolts. Their favorite food is clams and to detect them, they turn their long inhalant syphon in the direction of the current. They have a combined taste/smell organ in the syphon that can locate food at a considerable distance. The whelk then uses its large muscular foot to pry open the clam shell and inserts its radula and proboscis to remove the soft tissue inside.Sand dollar are left behind by the receding tide. In life, these animals have a felt-like coating of fi ne, brown movable spines. Their notches and holes provide a short cut for food bits traveling from their topside to their mouth.Florida fi ghting conchs are so named because of occasional bouts between rival males. They can quickly fl ip themselves and walk using their pointed operculum and eat sea-grass. The smaller crown conch is carnivorous and often preys on clams, mussels and oysters and is also known to be cannibalistic.Loggerhead sea turtle nests are clearly marked on Marco beach. Each nesting female makes an average of four nests, separated by two week intervals during the May-August nesting season. They typically take off 1-3 years between nesting trips, since the journey and laying 75-150 eggs per nest is so strenuous. Nests hatch be-tween July to October.All of this life is a sign of a healthy beach, which of course would not be possible without the sun. But everyone looks forward to its setting, and the two sunset scenes taken on that same walk, were particularly beautiful. So, go on, walk the beach and see what you can fi nd, but remember replace anything that is alive or you're not sure about.