Ecdysozoa and Arthropoda Lecture

Flashcards covering the classification, anatomy, and biological processes of Ecdysozoans, specifically Nematoda, Tardigrata, and various subphyla of Arthropoda.

Ecdysis

The ability to molt a nonliving outer layer of the body to allow for growth or metamorphosis.

Phylum Nematoda

Commonly known as roundworms, these organisms are unsegmented, round in shape, and possess a pseudo-coelum.

Ubiquitous

A term meaning an organism is found everywhere, living in all kinds of conditions and environments.

Dioecious

Organisms that have separate sexes, meaning there are distinct male and female individuals.

Turbatrix

The genus name for vinegar eels, a type of nematode that lives in acidic environments and moves with a side-to-side, eel-like motion.

Longitudinal Muscles

The only type of muscle layer found in nematodes, allowing for side-to-side contraction but not the complex movement seen in earthworms.

Sexual Dimorphism

The condition where males and females of a species exhibit different forms or shapes; in nematodes, males are often shorter with a hooked tail.

Ascaris

A genus of parasitic nematode known as the human intestinal roundworm.

Trichinella

A parasitic nematode that causes trichinosis, often acquired by eating undercooked pork containing larval cysts embedded in the muscle.

Dirofilaria

The genus of the dog heartworm, which is transmitted by mosquitoes and develops in the host's heart after traveling through the bloodstream.

Phylum Tardigrada

Commonly called water bears, these protostomes have bilateral symmetry, unjointed lobopodal appendages with claws, and are known for surviving extreme environments.

Tun State

A state of extreme desiccation or suspended animation where a tardigrade becomes like a freeze-dried organism, allowing it to survive extreme temperature, pressure, and radiation.

Stylets

Tooth-like structures in the mouth of a tardigrade used to impale prey.

Parthenogenesis

A form of reproduction used by some tardigrades where offspring develop from unfertilized eggs.

Phylum Arthropoda

The largest phylum on Earth, characterized by jointed appendages, segmented bodies, and an open circulatory system.

Chitin

A tough, durable structural material that makes up the nonliving cuticle or exoskeleton of arthropods.

Hemolymph

The circulatory fluid found in arthropods, which is a combination of lymph and blood-like fluid.

Tagmata

Specialized body regions, such as the head, thorax, and abdomen, formed by the fusion of segments.

Class Chilopoda

The class of myriapods known as centipedes, which have one pair of legs (two legs total) per body segment and a poisonous claw.

Class Diplopoda

The class of myriapods known as millipedes, which possess two pairs of legs (four legs total) per body segment.

Subphylum Chelicerata

A group of arthropods named for their first pair of mouth appendages (chelicerae) and characterized by having a cephalothorax and abdomen.

Chelicerae

The first pair of appendages near the mouth in chelicerates, used for feeding, defense, or modified into fangs.

Pedipalps

The second pair of appendages in chelicerates used for grabbing food or other specialized functions.

Class Merostomata

The class containing horseshoe crabs, which are described as living fossils that have remained unchanged for over 350 million years.

Book Gills

Respiratory structures in horseshoe crabs made of thin tissues stacked together like pages in a book.

Telson

A tail-like structure used as a rudder in horseshoe crabs, or the central part of the tail flipper in crayfish.

Class Arachnida

A class including spiders and scorpions, featuring eight walking legs, spinnerets for silk production, and book lungs.

Subphylum Crustacea

A diverse group including shrimp, crabs, and crayfish, characterized by biramous appendages and two pairs of antennae.

Biramous

A type of appendage that branches into two parts at the end, found in crustaceans.

Mandibles

Strong, club-shaped jaws in crustaceans and insects that move side-to-side to break up food.

Swimmerets

Specialized appendages on the underside of a crustacean's abdomen used for swimming and, in females, holding eggs.

Uropods

Flipper-like structures located on either side of the telson at the end of a crustacean's abdomen.

Subphylum Hexapoda

A group of arthropods characterized by having six legs, including the class Insecta.

Spiracles

Openings on the side of an insect's body that allow air to enter the tracheal system for gas exchange.

Malpighian Tubules

Specialized tubes used by insects for the excretion of waste.

Ommatidium

The individual functional units or lenses that make up the compound eyes of insects.

Tympanum

A hearing structure or eardrum found in insects, such as on the abdomen of a grasshopper.