Taxonomic Classification and Comparative Anatomy of Deuterostomes and Vertebrates

Vocabulary practice flashcards covering taxonomic classification, external and internal anatomical structures, integumentary features, and skeletal characteristics of deuterostomes and vertebrates.

Deuterostomes

A major group of animals defined by specific embryonic development patterns, encompassing Echinodermata, Hemichordata, and Chordata.

Five Defining Chordate Features

The five fundamental morphological characteristics shared by all chordates at some stage of development: notochord, pharyngeal slits, endostyle, dorsal hollow nerve cord forming the CNS, and postanal tail.

Endostyle

A ciliated glandular groove located in the pharynx of lower chordates used for filter feeding, which is homologous to the thyroid gland in higher vertebrates.

Phylum Hemichordata

A phylum of marine worms (such as acorn worms, e.g., Saccoglossus kowalevskyi) possessing pharyngeal gill slits, tornaria larvae, and a stomochord/primitive notochord that extends from the digestive tract into the proboscis region.

Class Ascidiacea

A class in Subphylum Urochordata characterized by a free-swimming larval stage and a sessile adult stage where the tail is reabsorbed.

Class Larvacea

A class of urochordates featuring a free-swimming larval form that matures inside secreted mucous houses and retains its tail throughout adulthood.

Class Thaliacea

A class of urochordates that exist as free-swimming planktonic drifters throughout their entire life cycle.

Subphylum Cephalochordata

Lower chordates (such as Amphioxus or Branchiostoma lanceolatum) that resemble early chordate ancestors and retain all five core chordate characteristics into adulthood.

Ammocoetes Larva

The free-swimming larval stage of sea lampreys (Petromyzon marinus) that possesses an amphioxus-like body organization.

Superorder Myxinoidea

Hagfishes (e.g., Myxine glutinosa); jawless marine vertebrates in Class Agnatha characterized by a single external gill opening or row of round gill slits, mucous pores along the body sides, a nasopharyngeal canal, and absent eyes.

Superorder Petromyzon

Sea lampreys; jawless round-mouth fishes in Class Agnatha featuring a buccal funnel lined with soft papillae, a rasping tongue, dorsal fins, and lidless eyes.

Class Chondrichthyes

Cartilaginous fishes lacking true bone except in scales and teeth, featuring a ventrally located mouth, placoid scales, and pelvic claspers in males for internal fertilization.

Order Holocephali

Cartilaginous fishes such as Chimaera sp. (ratfish) characterized by a large head with prominent staring eyes, pelvic claspers, and an opercular fold covering the gill slits.

Subclass Actinopterygii

Ray-finned fishes in Class Osteichthyes characterized by fin-supporting lepidotrichia, a bony operculum covering the gills, and scales over the trunk and tail.

Order Holostei

Non-teleost bony fishes such as Lepisosteus (the gar pike) featuring elongated toothed jaws, spiracles, and thick ganoid scales.

Order Teleostei

Typical bony fishes possessing well-developed jaws, homocercal caudal fins, and cycloid or ctenoid scales.

Subclass Lissamphibia

Modern amphibians characterized by smooth, moist, naked skin with few minute concealed scales, residing in aquatic or damp terrestrial habitats.

Order Urodela

Amphibians with permanent tails, including salamanders and mudpuppies (e.g., Necturus maculosus).

Order Anura

Tailless amphibians including frogs and toads (e.g., Bufo marinus, Rana vittigera, Rana catesbeiana).

Class Reptilia

Air-breathing ectothermic vertebrates whose body is covered in epidermal horny scales, plates, or tubercles, lacking gills throughout their entire life cycle.

Suborder Lacertilia

Lizards (e.g., Mabuya sp., Gecko gekko, Varanus salvator) typically possessing four limbs, movable eyelids, and external ears.

Suborder Ophidia

Snakes; limbless and eyelid-less reptiles covered in horny scales and head shields, featuring ventral shields, specialized jaws, and heat-detecting pits.

Order Chelonia

Turtles and tortoises possessing a body enclosed in a hard shell formed by a dorsal arched carapace and a ventral flat plastron.

Order Crocodilia

Large aquatic reptiles possessing both epidermal horny scales and dermal bony plates embedded in their skin (e.g., Crocodylus porosus).

Class Aves

Endothermic vertebrates characterized by epidermal feathers, forelimbs modified as wings, and toothless horny beaks.

Down Feather

Soft, fluffy feathers providing insulation in juvenile birds and at the base of adult contour feathers, consisting of a short quill, calamus, and long flexible barbs without interlocking hooklets.

Contour Feather

Vaned feathers that outline the bird's body and form flight surfaces, composed of a central shaft (rachis), a calamus, and an interlocking web of barbs and barbules.

Filoplume

Hair-like feathers visible on plucked birds, consisting of a slender main shaft with a small tuft of barbs at the terminal tip.

Pterylae and Apterylae

Pterylae are distinct skin tracts where feather follicles grow, whereas apterylae are the unfeathered skin spaces surrounding those tracts.

Class Mammalia

Warm-blooded vertebrates characterized by body hair or fur, mammary glands for nursing young, three middle ear bones, and an external ear pinna.

Types of Gaits in Mammals

Limb movement patterns categorized by foot posture during locomotion: plantigrade (sole flat on the ground, e.g., human), digitigrade (walking on toes/digits, e.g., cat), and unguligrade (walking on hoofed tips of digits, e.g., horse).

Integumentary Chromatophores

Pigment-containing dermal cells responsible for skin color, including melanophores (brown/black melanin), xanthophores/lipophores (yellow/fat-soluble pigments), and guanophores/iridocytes (reflective/iridescent crystals).

Fish Scale Types

Exoskeletal dermal scale structures in fishes, including placoid scales (tooth-like denticles in cartilaginous fishes), ganoid scales (heavy rhomboidal scales in non-teleost bony fishes), and cycloid/ctenoid scales (lightweight overlapping scales in teleosts).

Dermal Fin Rays

Dermal skeletal rods supporting fish fins, divided into ceratotrichia (keratinized rods in cartilaginous fishes), actinotrichia, lepidotrichia (segmented bony rays in osteichthyans), and camptotricha.

Mammalian Horn Types

Cranial integumentary structures including true horns (unbranched bony core covered by a permanent keratin sheath), antlers (branched bony growths shed annually in Cervidae), and hair horns (matted keratinized fibers, e.g., in rhinoceroses).