Arthropods - Armored Achievers

arthropods

Animals with a hard exoskeleton, jointed appendages, body segments, and bilateral symmetry

jointed appendages

limbs made of pieces that fit together, run by pairs of muscles, include legs, wings, mouth parts, and antennae

chitin

carbohydrate that forms part of the exoskeleton of arthropods, stiff

compound eyes

contain many lenses, good at sensing movement, stalked in most marine arthropods, have a wide field to view

molting

shedding the exoskeleton in order to grow larger, results in discontinous increases in size

tagmatization

modification of body segments for specific jobs, some segments may fuse together

nauplius

free-swimming larva of most crustaceans, triangular with 3 pairs of appendages and one eye

Crustaceans

majority of marine arthropods, crabs, copepods, lobsters, and shrimp, have 2 pairs of antennae, nauplius larvae, most have gills

isopods

Dorst-Ventrally flattened (squashed top to bottom), live on land, in freshwater, and in the ocean

decapod

Crustaceans that have five pairs of walking legs; a carapace and an abdomen, include shrimp, crabs, and lobsters

thorax

Body segment that is usually behind the head in insects, but fused with the head in crustaceans

abdomen

Usually the last body segment, the hind, contains reproductive organs and part of the digestive tract

antennae

Sensory structures that are able to detect movement, vibrations, and chemical signals/smells

swimmerets

small paired appendages located on the ventral surface of the abdomen of crustaceans used for swimming or reproduction

telson

flat structure at the end of the abdomen in crustaceans, the telson and uropods form the end of the tail

Examples of arthropods

insects, spiders, scorpions, crabs, lobsters, shrimp, copepods, and barnacles

cephalothorax

First body segment in crustaceans, head and thorax fused together, also called carapace

Three main body segments in insects

Head, thorax, abdomen

Exoskeleton

Hard, external, covering, jobs include protection, support, and movement, made of chitin and hardened with CaCO3 in marine arthropods, thickness varies over the body

Ecdysis

Process of removing the old exoskeleton, literally means "an escape." exoskeleton is split when animals take in water or air and increase their blood pressure

Copepods

Tiny abundant planktonic animals, drifters, filter feeders that love PPK, long antennae, segmented abdomen and thorax, no abdominal appendages, most have a single eye

Striated muscle

contracts very quickly compared to other types of muscle, multiple neurons signal contraction

Open circulatory system

Blood leaves the heart through closed vessels then dumps into body spaces before returning to heart

Arthropod reproduction

Sexual, most species have separate sexes, internal fertilization (land), external fertilization in most marine species

Class Merostomata

Two body portions, no antennae, only 4 living species all marine, includes horseshoe crabs which have a telson, 5 pairs of walking legs, and gill flaps

Rostrum

Sharp point coming off the head for defense, think shrimp

Mandibles, maxillae, and maxillipeds

Paired mouth parts in crustaceans used to manipulate and crush food

Zoea

first larval stage of crab, giant dorsal spine, big stalked eyes, and an abdomen, CUTE!

Megalops

second larval stage of crabs, looks like a mini-crab, abdomen is not tucked up yet, big stalked eyes

Green crab

invasive species in Maine, carapace has five spines and is shaped like a pentagon, fast and good at eating bivalves

Jonah crab, rock crab, red crab

native Maine species, oval carapace, 8-10 spines, may be as large as your hand, thick, muscular claws

Shrimp

extremely popular seafood, may be wild caught or farm-raised, elongated bodies, stalked eyes, slender legs, long antennae, first pair of appendages are not huge, pointy rostrum

Krill

8 pairs of walking legs, feathery gills visible, grow to about 6 cm, form enormous swarms, ecologically and commercially important, abundant in Antarctica, favorite food of seals, baleen whales, and birds

Metamorphosis

Change from larval to adult form. stages differ greatly in structure and appearance, requires molting

Chelipeds

First pair of appendages in lobsters and crabs, large, function in food capture and defense, may look the same or different (pincer and crusher)

Barnacles

Sessile as adults, enclosed by calcareous plates, reduced head, no abdomen, legs are long and form cirri which are used for filter feeding, common in intertidal zones in Maine

Crabs

dorsoventrally flattened, five pairs of walking legs, walk sideways, carapace, stalked eyes, first set of claws are large, abdomen tucked under

Lobsters

laterally compressed, five pairs of walking legs, carapace, stalked eyes, first set of claws are large, abdomen extended, commercially important Maine species

Asian shore crab

invasive species in Maine, carapace has three spines and is square-shaped, legs have light and dark bands

Season when most arthropod babies are born

SPRING - That's when the phytoplankton bloom, so food is abundant