K103 Chapter 32: The Deuterostomes

What are the ancestral features of deuterostomes?

Bilateral symmetry, triploblastic tissue layers, and a complete digestive system.

What are the derived features of deuterostomes?

Radial, indeterminate cleavage and formation of the anus from the blastopore.

What are the general characteristics of echinoderms?

Marine organisms

Pentaradial symmetry (in adults)

Calcareous endoskeleton( internal skeleton made of calcium carbonate)

Water vascular system

Regeneration capabilities

What are the main characteristics of class Asteroidea (sea stars)?

Typically five or more arms

Tube feet for movement and feeding

External digestion

What are the main characteristics of class Ophiuroidea (brittle stars)?

Slender, flexible arms

Rapid movement

Tube feet used for feeding, not locomotion

What are the main characteristics of class Echinoidea (sea urchins and sand dollars)?

No arms, rigid body

Movable spines

Flattened or globular body shape

What are the main characteristics of class Crinoidea (feather stars and sea lilies)?

Feather-like arms

Filter-feeding

Sessile or slow-moving organisms

What are the main characteristics of class Holothuroidea (sea cucumbers)?

Elongated, soft body: A long and flexible body that isn't hard.

Reduced skeleton: A smaller or less developed internal skeleton.

Evisceration as a defense mechanism: The ability to expel internal organs to escape danger, often as a way to confuse or distract predators.

What are the four shared derived traits of chordates?

Notochord

Dorsal hollow nerve cord

Pharyngeal slits

Post-anal tail

What are the additional features of vertebrates?

Vertebral column (backbone)

Skull

Well-developed brain

Specialized sensory organs

What are the characteristics of Urochordata (tunicates)?

Sessile marine filter feeders

Chordate traits present only in the larval stage

What are the characteristics of Cephalochordata (lancelets)?

Retain chordate features throughout life: Keep the main characteristics of chordates, like a notochord (a flexible rod), even as adults.

Burrow and filter feed in marine environments: Live by digging into the ground and feeding on tiny organisms in the water by filtering them out.

What are the major vertebrate groups in the cladogram?

Craniates

Vertebrates

Tetrapods

Amniotes

What are Craniates?

Animals that possess a skull (e.g., hagfish)

What are Vertebrates?

Animals with a vertebral column (e.g., fish, amphibians)

What are Tetrapods?

Four-limbed vertebrates (e.g., amphibians, mammals)

What are Amniotes?

Tetrapods that lay amniotic eggs (e.g., reptiles, birds, mammals)

What are the major vertebrate classes?

Agnatha: Jawless fish (e.g., hagfish, lampreys).

Chondrichthyes: Cartilaginous fish (e.g., sharks, rays).

Osteichthyes: Bony fish (ray-finned and lobe-finned).

Amphibia: Frogs, salamanders.

Reptilia: Turtles, snakes, lizards.

Aves: Birds.

Mammalia: Monotremes, marsupials, placentals.

What is oviparous reproduction?

Egg-laying, where fertilization occurs outside the body (e.g., birds, amphibians, reptiles)

What is viviparous reproduction?

Live birth with the embryo developing inside the mother's body, connected by a placenta (e.g., most mammals)

What is ovoviviparous reproduction?

Eggs develop inside the mother's body and hatch internally, but there is no placenta (e.g., some sharks, snakes)

Ray Finned Fish

Thin, flexible fins supported by bony rays (e.g., trout).

Lobe Finned

Fleshy, limb-like fins with internal bones (e.g., coelacanths, ancestors of tetrapods)

How did land-dwelling tetrapods evolve from lobe-finned fish?

Stronger bones

Limb-like fins for movement in shallow waters

Adaptation of lungs for breathing air, leading to amphibians

What are the two clades of modern birds?

Paleognathae: Flightless birds with a primitive palate (e.g., ostriches, emus).

Neognathae: Birds with strong flight adaptations (e.g., songbirds, hawks).

What are Monotremes (Prototheria)?

Egg-laying mammals that are the most primitive group of living mammals (e.g., platypus, echidna).

What are Marsupials (Metatheria)?

Mammals with a pouch where young develop after birth (e.g., kangaroos, koalas)

What are Placental Mammals (Eutheria)?

Mammals that give live birth with a placenta to nourish the developing fetus (e.g., humans, whales, elephants).