Zoology Exam 3

Echinoderms like sea stars have a unique _____ system.

Water vascular system

Water vascular system

System of canals and tube feet used for locomotion, predation, food and waste transport, and respiration

A

Madreporite; Sieve or filter like structure on upper surface that draws in water

F

Podium; sucker-like structures

B

Radial canal

C

Central ring canal

D

Tube foot; made up of ampullae

E

Ampulla; bulb like structures

What are two ways that most members of the phylum echinodermata differ from all other bilaterally symmetrical animals?

Adults with pentaradial symmetry; lack of a head region (no cephalization)

Describe the specialized methods for feeding on bivalves seen in the class asteroidea (sea stars)

Two stomachs, one can be everted through their mouths or secreted as digestive juices into or onto their prey before ingestion; they can digest bivalves while still alive and inside their own shells

Aristotle’s lantern

Found in class echinoidea (urchins); used for feeding on algae

A

Notochord

Notochord

A flexible, rod-shaped mesodermal strucutre that is found in the embryonic stage of all chordates and in the adult stage of some Chlorate species

B

Dorsal hollow nerve cord

Dorsal hollow nerve cord

Dorsal to notochord, developed into the brain and spinal cord

C

Post anal tail

Post anal tail

Posterior elongation of the body, extending beyond anus; contains skeletal elements and muscles; locomotion, balance, courting, and signaling

D

Pharyngeal gill slits

Paryngeal gill slits

Openings behind the mouth that extend to outside world; develop into gill and jaw supports in fishes; ears, tonsils, thymus, hyoid and jaw supports in tetrapods

Which group of invertebrate chordates have an adult body plan that closely resembles the ancestral condition of all chordates

Cephalochordata (lancelets)

Which group of invertebrate chordates has a larval stage with a body plan that closely represents the ancestral condition of all chordata, that is lost in the adult stage

Urochordata (tunicates, sea squirts, salps)

What are two characteristics of Agnathans that distinguish them from Gnathostomes

Lack of jaws and lack of paired lateral appendages (fins)

Why are hagfishes (myxini) considered part of the Craniata but not part of the Vertebrata?

They have a cranium but no vertebral column (notochord fully developed instead)

Lamprey lifecycle

Eggs are fertilized externally and the larvae (ammocoetes) differ greatly from the adult form, closely resembling the adult cephalocordates; after spending 3 to 15 years as suspension feeders in the substrate of rivers and streams, they eventually attain sexual maturity; shortly afterward, the adults swim upstream, reproduce, and die within days

Heterocercal

Caudal fin has unequally sized fin lobes, with the tail vertebrae extending into the larger upper lobe

Homocercal

Caudal fin has equally sized upper and lower fin lobes, with numerous fine bones radiating out from terminal vertebra

Two specialized sensory systems that first evolved in members of the class Chondrichthyes

ampullae of Lorenzini; lateral line system

Ampullae of Lorenzini

Detects electromagnetic fields of living things

Lateral line system

Detects movement and vibrations in water

Four ways that chimaeras and ratfishes differ from other members of the class Chondrichthyes

Diphycercal tail (equally sized fin lobes with the tail vertebrae located between them), lack scales (lost secondarily in evolution), teeth modified as grinding plates (used to feed on mollusks and other invertebrates); gill slits not exposed (covered with operculum)

Three groups of ray finned fishes

Acipenseriformes, Holostei, teleostei

Acipenseriformes

Sturgeons (27 species) and paddlefishes (2 species); have heterocercal tails, primitive jaws

Holostei

Gars (7 species) and bowfins (1 species, can breath air); have homocercal tails, primitive jaws

Teleostei

Over 26,000 species in 448 families; homocercal tails, advanced jaws (“deadly pucker”)

Importance of lobe-finned fishes (sarcopterygii) in the evolution of tetrapods

Lungfish have complex lung structures homologous to the lungs of modern tetrapods; tiktaalik fossil is a link between lobe finned fish and 4-legged amphibians

Difference between amphibian life cycle and other tetrapods life cycles

Amphibians go through metamorphosis from an aquatic larva to a terrestrial adult; no other tetrapods undergo metamorphosis in the environment

Three orders of amphibians

Anura, Urodela, Apoda

Anura

Frogs and toads; continuous bodies, no ribs, no teeth on lower jaw, tailless adults, 7,400 species

Urodela

Salamanders; head distinct from body, ribs present, teeth on lower jaw, adults with tails, 765+ species

Apoda

Caecillans, legless, cylindrical bodies, vestigial eyes, retractable sensory tentacles, 215+ species

Why is the amniotic egg such an important evolutionary innovation

Key adaptation for the colonization of land, making reproduction independent from aquatic habitants allowing amniotes to adapt to all terrestrial habitats

5

Albumen

4

Chorion

3

Allantois

2

Amnion

1

Embryo

Amnion

Fluid filled cavity that provides the embryo with its own internal aquatic environment; protects the embryo from mechanical shock and supports hyrdation

Allantois

Stores nitrogenous wastes produced by the embryo and facilitates respiration

Chorion

Facilitates exchange of oxygen and carbon dioxide between the embryo and the egg’s external environment

Albumin

Egg white, outside of the chorion provides the embryo with water and protein

Yolk

Contained in the yolk sac and provides nutrients for the embryo

Three major lineages of Amniota

Anapsids, synapsids, diapsids

Anapsids

No temporal fenestra (extinct parareptiles)

Synapsids

Have a single temporal fenestra (modern mammals)

Diapsids

Have two temporal fenestra (turtles, Lepidosauria, archosaurs)

4 key characteristics shared between crododilians and birds that reflect both are descended from a common ancestor in archosauria

Four chambered hearts, nest building and brooding, prolonged parental care of hatchlings, use of vocalizations for communication

Six characteristics that birds evolved that are linked to their ability to fly

Endothermic and homeothermic (generate and maintain a constant elevated body temperature), high metabolic rate (due to flight), pneumatic (hollow) bones, feathers (modified scales, also used for insulation), sternum in shape of keel (large surface for flight muscle attachment), efficient respiration

Arboreal hypothesis

Tree dwelling ancestors to modern birds jumped from branch to branch using their feathers for gliding before becoming fully capable of flapping flight

Terrestrial hypothesis

Running (perhaps pursuing active prey such as small animals) was the stimulus for flight; wings could be used to capture prey and were pre adapted for balance and flapping flight

Palaeognathae

Ratites (ostriches, emus, rheas, cassowaries, tinamous, kiwis); precocial hatchlings (capable of feeding and moving on their own almost immediately)

Neognathae

All other birds; with altricial hatchlings (born in underdeveloped state that requires feeding and care from parents); some are semi-precocial or semi-alticial)

Pleurodira

“Side neck”; retract their neck horizontally, folding their neck to the side

Cryptodira

“Hidden neck”; retract their neck backward in a vertical S-curve

Hemipenes

Paired reproductive organs

Jacobson’s organ

Secondary olfactory sense organ (aka vomeronasal organ)

Pedicellate teeth

The root and crown are calcified, separated by a zone of non calcified tissue

Respiratory trees

Class holothuroidea; pair of gill-like structures that branch from the posterior gut; muscles around the cloaca pump water in and out of these

Class holothuroidea

Deeds on detritus, some are suspension feeders; unique echinoderms in having circulatory cells containing hemoglobin