Phylum Arthropoda

Kingdom Animalia

Phylum Arthropoda

Subphylum Crustacea

Class Cirripedia

Class Copepoda

Class Malacostraca

Order Decapoda

Order Euphausiacea

Subphylum Chelicerata

Class Merostomata

Class Pycnogonida

Arthropods Largest phylum of

animals 1 million species

(some estimates say up to 20 million)

Includes mainly terrestrial bugs

3 out of every 4 animals are arthropods

General Characteristics of Arthropods

Segmented body Bilateral Symmetry Jointed

appendages Chitinous

exoskeleton

Sub Phylum Crustacea

Includes: Shrimps Crabs Lobsters Barnacles Potato Bugs

(terrestrial)

General Characteristics of Crustaceans

Two pairs of antennae

Mandibles for chewing

Pair of appendages on each body segment

Gills for oxygen

Molting

To grow, arthropods must molt their exoskeleton

Digestion Smaller crustaceans

are filter feeders, catching particles in bristles on their appendages

Some have specialized appendages that push food towards their mouths

Nutrients passed to an open circulatory system

Nervous System

Can vary from simple ladder-like to centralized nervous systems

Most have compound eyes

Keen sense of smell Communicate with

each other via body postures

Compound Eyes

Bundles of up to 14,000 light sensitive units grouped together

Some on stalks that can be used like periscopes

Class Cirripedia

Filter feeders Attached to surfaces

including living ones Look like mollusks

because of their shells Others lack plates and

are highly developed parasites

Class Copepoda

Abundant and important in the role of plankton

Can use their antennae to swim

“Sea Monkeys”

Importance of Copepods

1. Most numerous multi-cellular animals on Earth

2. Eat the tiniest plankton and are in turned eaten by fish & krill

3. Fecal pellets shorten the nutrient cycle of the ocean

Order Decapoda

“ten legs” Largest

crustaceans in terms of size

Extended carapace Shrimp, lobsters,

and crabs

Order Decapoda

Five pairs of walking legs (pereopods) of which one is usually heavier (claws)

Carapace encloses the cephlalothorax with the rest of the body being the abdomen

Order Decapoda

Shrimp and lobsters can range from scavengers to parasite removers

Crabs tend to be scavengers

Order Euphausiacea Krill Planktonic Shrimp-like Head fused with body

pieces to form a unique carapace

Major food source for larger organisms (whales, seals, penguins, etc.)

Sub Phylum Chelicerata Includes Horseshoe

crabs, spiders, mites Chelicerae are the

only small appendages before the mouth

Range from small pinchers to venomous fangs

Class Merostomata Horseshoe Crabs Not true crabs and have

not evolved for millions of years

Six pairs of appendages No mandible jaw Chelicerae, Walking Legs,

four pairs of Pushing Legs Telson or tail used for

steering and flipping itself right side up.

Class Pycnogonida

Sea Spiders Have four or more pairs of

legs A large proboscis with a

moth on the tip allows it to feed on soft invertebrates

No respiratory system as gases diffuse through body

Tiny muscles consist of one cell covered with connective tissue