Lecture 24 (2) Vocabulary (BIOL211)

Comprehensive vocabulary terms and definitions covering Ecdysozoans, Arthropods, Deuterostomes, and Chordates based on lecture notes.

Ecdysozoa

A clade of protostome animals characterized by the possession of a cuticle and the process of molting.

Cuticle

The non-living outer layer secreted by the epidermis in Ecdysozoans.

Ecdysis

The process of molting, or shedding the old cuticle, to allow for growth.

Nematode

A member of the phylum Nematoda, commonly referred to as roundworms.

Cranium

The bony or cartilaginous structure that encloses and protects the brain.

Vertebral column

The series of vertebrae extending from the skull to the pelvis, forming the main support of the body in vertebrates.

Gnathostome

A member of the vertebrate group characterized by the possession of jaws.

Cyclostome

A group of jawless vertebrates that includes hagfishes and lampreys.

Tunic/Tunicate

A member of the Urochordata subphylum, characterized by a tough outer covering called a tunic.

Ascidian

A class of tunicates commonly known as sea squirts.

Thaliacean

A class of free-floating, barrel-shaped tunicates.

Larvacean

A class of tunicates that retain their larval characteristics, including a tail, throughout adulthood.

Arthropod

An invertebrate animal belonging to the phylum Arthropoda, featuring an exoskeleton, a segmented body, and paired jointed appendages.

Open circulatory system

A system where fluid called hemolymph is pumped into a cavity called the hemocoel, bathing the organs directly.

Gills

Respiratory organs used by aquatic arthropods for gas exchange.

Lungs

Respiratory organs used by terrestrial arthropods, such as book lungs in arachnids, for gas exchange.

Chelicerates

A subphylum of arthropods characterized by having chelicerae and lacking antennae.

Chelicerae

The first pair of appendages in chelicerates, often used for feeding or defense (e.g., fangs).

Pedipalp

The second pair of appendages in chelicerates, used for sensing, feeding, or reproduction.

Pycnogonid

Commonly known as sea spiders, these are marine chelicerate arthropods.

Horseshoe crab

Marine chelicerates known for their hard, bowl-shaped carapace and long tail spine.

Arachnid

A class of chelicerates that includes spiders, scorpions, ticks, and mites.

Myriapod

A subphylum of arthropods with many body segments and legs, including centipedes and millipedes.

Pancrustacea

A clade of arthropods that includes both crustaceans and hexapods.

Crustacean

A large group of arthropods, such as crabs and lobsters, typically having two pairs of antennae and branched appendages.

Nauplius

The first larval stage of many crustaceans, characterized by three pairs of appendages and a single median eye.

Tracheae

A system of branching tubes used for respiration in many terrestrial arthropods.

Complete metamorphosis

A type of insect development consisting of four distinct stages: egg, larva, pupa, and adult.

Incomplete metamorphosis

A type of insect development where the young (nymphs) resemble small versions of the adult and undergo a series of molts.

Deuterostome

A major clade of animals characterized by the blastopore developing into the anus.

Pharyngeal slits

Openings in the pharynx that serve functions ranging from filter-feeding to gas exchange, found in chordates at some stage of development.

Hemichordate

A phylum of marine deuterostome animals, such as acorn worms, that share some traits with chordates.

Echinoderm

A phylum of marine animals, including sea stars, brittle stars, sea urchins, and sea cucumbers, characterized by a water vascular system.

Pentaradial symmetry

A form of radial symmetry where body parts are arranged in fives, characteristic of adult echinoderms.

Water vascular system

A network of hydraulic canals unique to echinoderms used for locomotion, respiration, and feeding.

Chordates

A phylum recognized by the possession of a notochord, dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.

Cephalochordate

A subphylum of chordates, commonly known as lancelets, that retain chordate traits throughout their lives.

Fins

Appendages used by aquatic chordates for locomotion and stability.

Lancelet

A small, blade-shaped cephalochordate that lives in marine sands.

Urochordate

A subphylum of chordates, also known as tunicates, where most chordate traits are prominent only in the larval stage.

Tadpole larva

The free-swimming larval stage of urochordates that possesses all four hallmark chordate characteristics.