Animal Diversity: Protostomes (Arthropods) & Deuterostomes

Flashcards covering key vocabulary, morphology, respiration, reproduction, and evolutionary success of arthropods, and the defining characteristics and diversity of deuterostomes, including echinoderms, jawless fishes, cartilaginous fishes, bony fishes, amphibians, reptiles (including birds), and mammals.

Arthropods

Invertebrates with an exoskeleton and jointed legs; 'arthro' means jointed and 'pod' means foot.

Ichthysozoan

A lineage on the phylogenetic tree that includes nematodes and arthropods.

Jointed Appendage

Growth from the body of an organism that has a joint in it, such as legs, wings, or mouthparts in arthropods.

Chitin

A hard, thick carbohydrate that makes up the exoskeleton and jointed appendages of arthropods.

Waxy Layer (Arthropods)

Part of the exoskeleton in land arthropods that protects against water loss.

Tracheae

A network of tubes used for respiration in terrestrial arthropods, allowing for air diffusion and compression/relaxation.

Gills

Respiratory organs found in aquatic arthropods.

Book Lungs

A type of lung found in spiders and horseshoe crabs for respiration.

Arthropod Body Segments

Typically three fused segments: head, thorax, and abdomen.

Cephalothorax

A fused head and thorax segment found in some arthropods.

Exoskeleton

A hard outer shell in arthropods that provides muscle attachment and protection, but limits growth size.

Molting

The process by which arthropods shed their rigid outer exoskeleton to allow for growth, shedding of parasites, and regeneration of lost legs.

Calicerata

A subphylum of arthropods including scorpions, spiders, and mites, characterized by first appendages modified into pincers or fangs, and mostly predatory feeding habits.

Crustaceae

A subphylum of arthropods that are dominant marine arthropods (crabs, shrimps, barnacles) and include some terrestrial forms (sow bugs, pill bugs), with branched appendages and antennae.

Myriapata

A subphylum of arthropods meaning 'lots of legs and many segments', including millipedes and centipedes.

Hexapoda

The largest subphylum within Arthropoda, encompassing classic insects with three body sections and six legs (e.g., dragonflies, bees, butterflies).

Described Species

A species that has been formally discovered and described in a taxonomic sense.

Complete Metamorphosis

A change in body plan during development where an animal passes through distinct life stages (egg, larva, pupa, adult) that look completely different from each other, allowing for specialization.

Incomplete Metamorphosis

A type of metamorphosis where juvenile versions of an animal resemble miniature versions of the adult.

Deuterostomes

A group of animals where the anus develops first, and the mouth develops second ('mouth second' in Greek), including echinoderms and chordates.

Echinodermata

A major group of deuterostomes named for their spiny skin ('echinos' means spiny, 'dermos' means skin), exclusively marine species like sea stars, sea urchins, and sand dollars.

Pentaradial Symmetry

A type of radial symmetry found in adult echinoderms where rays or arms are arranged in groups of five.

Endoskeleton (Echinodermata)

An internal skeleton of interlocking calcium carbonate plates covered by an epidermis in echinoderms.

Water Vascular System

A physiological system in echinoderms consisting of a central ring and radial canals filled with water, used for circulation and operating tube feet.

Tube Feet

Manipulable structures in echinoderms, controlled by water pressure, used for movement, feeding, and attachment.

Evert (Stomach)

To turn inside out, as demonstrated by sea stars pushing their stomach into a bivalve's shell to digest its contents.

Chordata

A diverse group of deuterostomes including vertebrates (fish, amphibians, reptiles, mammals) and two smaller invertebrate groups (tunicates, lancelets).

Dorsal Hollow Nerve Cord

A defining feature of chordates, a hollow cord containing nerves located on the dorsal side of the body.

Notochord

A flexible rod that supports the nerve cord for at least part of life in chordates, replaced by the vertebral column in vertebrates.

Vertebral Column

The vertebrae that replace the notochord and surround the nerve cord in vertebrates.

Osmoregulatory

The ability of an organism to control solute levels in its cells, particularly salts.

Estuary

A brackish area where salty ocean water and freshwater mix, often exploited by early osmoregulatory fish.

Jawless Fishes

The first group of modern fishes, examples include hagfish and lampreys.

Cartilaginous Fishes

Fish whose skeleton is made of cartilage, such as sharks and rays.

Ray-finned (Bony) Fishes

The third and most diverse group of fish, where cartilage is replaced by a bony skeleton (e.g., seahorses, clownfish).

Swim Bladder

A modified lung-like sac in ray-finned fishes that evolved for respiration and provides buoyancy, allowing them to stay motionless at particular depths.

Amphibians

The first vertebrates on land, mostly confined to moist habitats, with lungs and skin respiration, and external fertilization in water (e.g., frogs, toads, salamanders).

Reptiles

Vertebrates better adapted to dry land with scaled skin, internal fertilization, and waterproof eggs; includes birds as a monophyletic group (e.g., lizards, snakes, crocodiles, birds).

Monophyletic Group

A group consisting of a common ancestor and all its descendants.

Mammals

Vertebrates characterized by hair (made of keratin) and mammary glands that produce milk, with diverse morphology and ecology but relatively few species.

Monotremes

Egg-laying mammals with reptilian-like splayed legs (e.g., platypus, echidna).

Marsupials

Mammals that give birth to small young and nurse them in a ventral pouch (e.g., kangaroo, wombat, koala).

Eutherian Mammals

Placental mammals, the most diverse group within mammals (over 4,000 species), characterized by a placenta for embryonic nutrition (e.g., bats, whales, humans).

Placenta

An organ that forms where the embryo contacts the mother's uterus lining, providing nutrition to the embryo in eutherian mammals.