Nematoda

Dioecious

Having distinct male and female individuals.

Pseudocoelom

A body cavity not completely lined with mesoderm, found in nematodes.

Complete digestive tract

Digestive system with both a mouth and an anus.

Hydrostatic skeleton

Fluid-filled pseudocoelom that provides support and movement.

Genus: Ascaris

A genus of parasitic roundworms, often used in dissection.

Male vs. female (external)

Males are generally smaller and have a curved tail; females are larger and straight.

Lateral lines

Excretory canals visible on the sides of nematodes.

Dorsal and ventral nerve cords

Main components of the nervous system running along the back and belly.

Testis

Male reproductive organ producing sperm.

Vas deferens

Tube that transports sperm from the testis.

Seminal vesicle

Stores and releases sperm during reproduction.

Ovaries

Female reproductive organs producing eggs.

Oviducts

Tubes that carry eggs from ovaries to the uterus.

Uterus (uteri = plural)

Where fertilized eggs develop.

Vagina

Opening for the reproductive tract in females.

Genital pore

External opening for reproductive and sometimes excretory functions.

Pharynx

Muscular organ for sucking in food.

Intestine

Tube for nutrient absorption.

Cuticle

Tough, flexible outer covering.

Epidermis

Layer underneath the cuticle that secretes it.

Longitudinal muscles

Muscles running lengthwise, allowing thrashing movement.

Jointed appendages

Legs, antennae, and other structures with joints for mobility.

Segmented body

Body divided into repeating segments.

Exoskeleton

Hard outer covering made of chitin for protection and support.

Molting

Shedding of the exoskeleton to allow growth.

Coelom

True body cavity fully lined with mesoderm.

Hemocoel

Body cavity filled with hemolymph (blood-equivalent fluid).

Open circulatory system

Blood not entirely contained in vessels.

Cerebral ganglia

Brain-like clusters of nerve cells.

Ventral nerve cord

Nerve cord running along the belly side.

Gills

Organs for gas exchange in aquatic arthropods.

Book lungs

Respiratory structures with stacked plates in arachnids.

Tracheae

Air tubes used for breathing.

Spiracles

Openings on the body for air intake.

Subphylum Chelicerata

Includes horseshoe crabs and arachnids.

Class Merostomata

Includes horseshoe crabs.

Class Arachnida

Includes spiders, scorpions, and ticks.

Subphylum Myriapoda

Includes centipedes and millipedes.

Class Chilopoda

Includes centipedes.

Class Diplopoda

Includes millipedes.

Subphylum Crustacea

Includes crabs, lobsters, and shrimp.

Class Malacostraca

Includes crabs, lobsters, and shrimp.

Subphylum Hexapoda

Includes insects.

Class Insecta

Includes all insects.