Ecdysozoans and Deuterostomes Lecture Review

These vocabulary flashcards cover the key phyla, biological structures, and developmental processes of Ecdysozoans and Deuterostomes as described in the lecture notes.

Ecdysozoa

A clade of protostomes that includes animals covered by an extracellular layer called a cuticle; they must periodically molt to grow.

Cuticle

An extracellular layer found in ecdysozoans used for protection and skeletal support.

Ecdysis

The periodic process of shedding or molting the old cuticle and forming a new one to allow for growth.

Nematoda

A phylum of ecdysozoans that are unitary, pseudocoelomate, and often tiny parasitic or free-living worms found in damp habitats.

Caenorhabditis elegans

A crucial nematode model system in developmental biology; adults have a total of 959 somatic cells.

Arthropoda

A diverse phylum of unitary, coelomate, and segmented ecdysozoans characterized by a rigid cuticle and jointed appendages.

Hemolymph

The blood-like fluid found in the partially open circulatory system of arthropods.

Chelicerae

Head appendages in chelicerates used to grab food and sometimes inject poison.

Pedipalps

Head appendages in chelicerates used for sensing or grabbing food.

Myriapods

A clade of arthropods including centipedes and millipedes, characterized by a head and a long trunk.

Pancrustaceans

A clade composed of crustaceans (which are paraphyletic) and insects.

Tracheae

A system of long, narrow tubes in insects that deliver oxygen to all body organs via diffusion.

Incomplete Metamorphosis

Also called hemimetabolous development, where larval stages (instars) look basically like small adults at every molt.

Complete Metamorphosis

Also called holometabolous development, where the larva looks very different from the adult and undergoes a dramatic transformation during a pupal stage.

Deuterostomia

A clade of bilateria where embryos undergo radial cleavage, the blastopore forms the anus, and mesoderm develops from outpocketings of the archenteron.

Water Vascular System

A unique system of fluid-filled tubes in echinoderms that operates tube feet for locomotion, feeding, and gas exchange.

Hemichordata

A phylum of deuterostomes featuring a three-part body plan consisting of a proboscis, collar, and trunk.

Notochord

A dorsal rod of large, fluid-filled cells that serves as a rigid but flexible skeletal element in all chordates at some life stage.

Cephalochordata

Also known as lancelets, these are marine invertebrate chordates that retain the notochord throughout their lives.

Urochordata

Also known as tunicates, these are marine invertebrate chordates that possess a secreted exoskeleton called a tunic.

Vertebrata

A clade of chordates characterized by an anterior cranium and a jointed dorsal vertebral column that replaces the notochord during development.

Cyclostomes

A clade of jawless vertebrates including hagfishes (Myxini) and lampreys (Petromyzontida).

Hagfishes (Myxini)

Marine scavengers with a cartilaginous skeleton, no jaws, and the ability to secrete large amounts of slime.

Lampreys (Petromyzontida)

Cartilaginous vertebrates with filter-feeding larvae called ammocoetes; adults are mostly parasites of fish.

Cryptobiosis

A state of dormancy in which metabolic activities are virtually stopped, utilized by tardigrades and rotifers in temporarily wet habitats.