Zoology: Introduction to Protostomes, Deuterostomes, and Arthropods #4

Flashcards covering introductory concepts of animal development, echinoderms, nonvertebrate chordates, and the classification and behaviors of various arthropod groups.

Protostome

A group of organisms where the mouth develops from the first opening in the embryo and the anus is a later development.

Deuterostome

A group of organisms where the anus forms from the first opening and the mouth is the second evolutionary development.

Bobbit worm

A predatory marine polychaete that lives on the ocean floor and uses chemoreceptors to catch prey with extreme speed.

Sedentary

A term describing organisms that are immobile or sit in one place, such as marine fan worms.

Velvet worm

An ancient, nocturnal hunter found in wet forests that captures prey by squirting twin streams of sticky mucus.

Echinoderms

A phylum of deuterostomes that includes starfish, sand dollars, sea cucumbers, sea biscuits, and sea urchins.

Detritus

Decaying organic matter that is in the process of breaking down, used as a food source by detritivores like sea cucumbers.

Tunicates

A subphylum of chordates, commonly called sea squirts, that process organic material by running water through openings in their bodies.

Salps

Barrel-shaped, transparent, free-floating tunicates that move by jet propulsion and filter plankton using an internal mucus net.

Notochord

A primary chordate characteristic consisting of a supportive rod that is replaced by vertebrae in vertebrate species.

Arthropod

An organism characterized by jointed appendages (arthro-pod) and a hard exoskeleton.

Exoskeleton

A hard external skeleton that provides structural support, protection, movement, and water impermeability for arthropods.

Trilobites

An extinct group of marine arthropods often studied in the fossil record.

Chelicerata

A subphylum of arthropods with complex biting mouthparts called chelicerae, including spiders, ticks, scorpions, and horseshoe crabs.

Arachnida

A class of chelicerates characterized by having 8 legs, including spiders, scorpions, and chiggers.

Isopods

A group of crustaceans whose name means same feet because all their pairs of legs look identical.

Hexapods

A group of arthropods, including insects, characterized by having 6 legs.

Pancrustacea

A taxonomic clade that groups crustaceans and hexapods together based on the understanding that insects are nested within the crustacean branch.

Darwin's bark spider

A spider capable of creating $25\,m$ bridging lines and silk that is 10 times tougher than Kevlar.

Sexual cannibalism

A reproductive strategy where one mate consumes the other, which can provide nutrients for offspring and help ensure paternity.

Questing

The behavior where tick larvae crawl to the ends of grass stalks to wait for and latch onto a passing host.

Vinegaroon

A predatory arachnid that defends itself by spraying a chemical containing $80\%$ acetic acid.

Scorpions

Arachnids that glow under ultraviolet light due to fluorescent chemicals and use sensitive hairs to detect prey vibrations.

Horseshoe crabs

Ancient chelicerates that spawn on beaches like those in Delaware Bay, where females lay clusters of about $4,000$ to $5,000$ eggs.