Crabs, Lobsters, Shrimp, Barnacles, Horseshoe Crabs and More! Arthropods Crabs, Lobsters, Shrimp, Barnacles, Horseshoe Crabs and More!

Arthropod Characteristics Phylum: Arthropoda (Arthro = jointed, Pod = foot) Invertebrate with an external skeleton, jointed appendages, and a segmented body Over 80% of all animal species are Arthropods! Estimate: 1,000,000 spp. arthropods 1,190,000 spp. animals ~ 84% of all animal species are arthropods

Arthropod Characteristics The arthropod body plan consists of repeated segments, each with a pair of appendages Open circulatory system External Skeleton (exoskeleton) Skeleton does not grow with them, so they must molt

Open Circulatory System Blood is not contained in vessels All the organs are constantly bathed in hemolymph, a combination of blood and lymph Blood is drawn in to the heart through holes called ostia, then pumped out again to circulate through the tissues and return again to the heart.

Molting Exoskeleton cannot grow, so they replace their exoskeletons by molting, or shedding the old exoskeleton after growing a new one that is not yet hardened. Molting Time Lapse

Secretion of "molting fluid" to dissolve old endocuticle. Molting (Step 1) Secretion of "molting fluid" to dissolve old endocuticle.

Molting (Step 2) New cuticle formed under old exocuticle. Break out of old cuticle Old cuticle breaks at line of weakness

Molting (Step 3) Inflate with water/air to increase size while skeleton soft, but soft skeleton & gravity limit size; Hardening of new exocuticle. Vulnerable until new skeleton hardens

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Growth Stages Arthropod passes thru 3-20+ growth stages in life cycle. Some stop molting as adults (insects, most spiders) Some continue to molt (crayfish, tarantulas)

Reproduction in marine arthropods Sexes are typically separate Some species are hermaphroditic (barnacles) Internal fertilization: males have specialized appendages to transfer sperm to females

Chelicerates (arachnids) Crustaceans Marine Arthropods

Chelicerata (Arachnids) Includes spiders, mites, scorpions, ticks and horseshoe crabs—4 pairs of legs (8 legs total)

cHELICERATA Sea Scorpion (extinct) Sea Spider

Horseshoe crabs Horseshoe Crab Facts Common off of the Atlantic and Gulf coasts Large dorsal carapace bearing compound eyes Abdomen terminates in a long tail called the telson; used to turn the animal right side up Possess a series of gill plates called book gills Horseshoe Crab Facts

Crustaceans Includes lobsters, crabs, crayfish, barnacles, and shrimp Most are aquatic 5 pairs of walking legs

Copepods (Small Crustaceans) The smallest & most abundant crustacean Marine zooplankton Elongated antennae Filter feeding mouth

barnacles Usually live attached to a surface, including crabs and whales Surrounded by thick calcium plates Lie on their backs and use feathery appendages called cirri (attached to legs) to filter feed

Barnacles and Whales Symbiotic Relationship Barnacles get a place to live, protection from predators, and feed on plankton as the whale swims Whales are typically not bothered, and the barnacle “suit of armor” often protects them

decapods 5 pairs of legs (10 total), first pair are claws Lobsters, Crabs, Shrimp Largest groups of crustaceans (and very delicious!)

Japanese spider crab Largest crustacean in the world! Up to 12 feet wide from claw to claw

Mantis Shrimp Highly advanced eyes Modified claws to pack a deadly punch! True Facts about the Mantis Shrimp

Deep Sea Shrimp Spews a Bioluminescent Mucus Cloud!

How do you know this is a crab and not a spider? Arrow Crab How do you know this is a crab and not a spider? Fiddler Crab Fiddler Crab Waving

Crayfish dissection External Anatomy (Start at 4:00) Internal Anatomy