Life, Arthropods, and Arachnids - Lecture Notes Flashcards

A set of 50 flashcards covering taxonomy, cladistics, and arthropod biology from the lecture notes.

What does ICZN stand for in taxonomy?

International Code of Zoological Nomenclature.

What is Systematics?

Science of understanding relationships among organisms.

What is Phylogenetics?

Study of evolutionary relationships among organisms (phylogeny).

What is Cladistics?

A method of phylogenetic analysis to build evolutionary family trees.

In cladistics, what is a Character?

An observable aspect of an organism (morphology, genetics, behavior).

Define Plesiomorphy.

An ancestral state retained from ancestors.

Define Symplesiomorphy.

A shared ancestral character among groups.

Define Apomorphy.

A derived (newly evolved) character.

Define Autapomorphy.

A derived character unique to a single group.

Define Synapomorphy.

A shared derived character (shared apomorphy) among two or more groups.

What does Monophyletic mean?

A clade containing the most recent common ancestor and all its descendants.

What does Paraphyletic mean?

A clade containing the most recent common ancestor but not all descendants.

What does Polyphyletic mean?

A clade that does not include the most recent common ancestor.

What is Ecdysozoa?

A group with a three-layered cuticle and molting cycles; includes Nematodes, Onychophorans, Tardigrades, and Arthropods.

What is Cryptobiosis?

A state of metabolic suspension enabling survival in extreme conditions.

Name three synapomorphies of Phylum Arthropoda.

Tagmosis (body segmentation), a chitinous exoskeleton, and paired, segmented appendages.

What is the main body cavity of arthropods?

Open hemocoel.

Do arthropods have an open or closed circulatory system?

Open circulatory system.

How do arthropods respire?

Gills or tracheae with spiracles.

How do arthropods grow?

Growth by molting (ecdysis).

What excretory system is common in arthropods?

Malpighian tubules.

What is Hexapoda?

A subgroup of arthropods including insects and their six-legged relatives.

What is Pancrustacea?

A clade including crustaceans and hexapods (insects).

What is a Trilobite?

An early true arthropod with a complete exoskeleton; with one pair of antennae, one pair of eyes, and one pair of legs per body segment.

Approximately how many trilobite species exist?

Over 20,000 species.

When did trilobites live?

Early Cambrian to Late Permian (about 520–250 million years ago).

What is Biostratigraphy?

Linking rock age and location using fossils.

What is Tagmosis?

External and internal body segmentation with regional specialization.

What is a chitinous exoskeleton?

A tough external skeleton made of the polysaccharide chitin.

Name two early Arthropod features.

Tagmosis and paired, segmented appendages.

What are Chelicerata mouthparts called?

Chelicerae (modified appendages).

Do Chelicerata have wings?

No wings.

Do Chelicerata have antennae?

No antennae.

How many pairs of appendages do Chelicerata have?

Six pairs: one pair chelicerae, one pair pedipalps, and four pairs of walking legs.

Give an example of an order in Class Arachnida.

Araneae (spiders) or Opiliones (harvestmen).

What is Pycnogonida?

Sea spiders; a subphylum within Chelicerata.

What is Xiphosura?

Horseshoe crabs; an order of chelicerates.

What are Thelyphonida known as?

Vinegaroons or whip scorpions; spray acetic acid; no venom; mating dance; female carries young.

What are Amblypygi commonly called?

Tailless whip scorpions; no venom; female carries young; long pedipalps (whip-like).

What are Opiliones commonly called?

Harvestmen; not true spiders; defensive liquids; internal fertilization; lifespan up to 5 years.

What are Palpigradi known as?

Microwhip scorpions; very small; living in caves; first walking legs used as sensors; unknown function of flagellum.

What are Schizomida called?

Short-tailed whipscorpions; small; males mate via spermatophores; females protect eggs and young; harmless.

What are Ricinulei known as?

Hooded tick-spiders; small; no eyes; hood covers chelicerae; legs modified for spermatophore transfer; larvae are 6-legged.

What are Acari?

Mites (including ticks and chiggers); ~50,000 species; diverse lifestyles; larvae can have 6 legs; some spread disease.

What are Scorpiones?

Scorpions; ~1500 species; stinger-tipped tail; ovoviviparous; females carry young; some live up to 25 years.

What are Pseudoscorpiones?

Pseudoscorpions; ~3000 species; small; venom glands on pedipalps; stalked spermatophore; maternal care; phoresy; harmless.

What are Solifugae commonly called?

Camel spiders or wind scorpions; up to 12–15 cm; no spermatophore; male subdues female by chewing; usually harmless.

Describe Limulus polyphemus.

Atlantic horseshoe crab; one of four species of horseshoe crabs worldwide; ancient lineage.

Why is horseshoe crab blood blue?

Blood uses hemocyanin (copper) to transport oxygen.

What is LAL used for in medicine?

Limulus amebocyte lysate (LAL) test to detect endotoxins in vaccines and biologics.

Which species is the Atlantic horseshoe crab mentioned in the notes?

Limulus polyphemus.

How many life-important uses does horseshoe crab blood have in medicine?

Endotoxin testing via the LAL assay; essential for vaccine safety.

Where does one NC horseshoe crab species occur?

In North Carolina, the species Limulus polyphemus occurs.

How many horseshoe crab species exist worldwide?

Four species.

What year did limulus blood testing start being used widely for endotoxins?

Since 1977.

What is a major ecological note about horseshoe crab eggs?

Eggs are an important food source for Red Knot shorebirds; crab decline affects bird numbers.

What arresting fact about horseshoe crabs is highlighted in the notes?

They are living fossils with a long lineage (450,000,000 years).