BIOL 2200 ECOLOGY AND EVOLUTION EXAM 3

Lecture 22,

Animals first appeared approximately _____ MYA

710

The closest living relatives of animals are _______.

choanoflagellates

The largest adaptive raditoon of animals occurred during the ___________

Cambrian Explosion

Animals were entirely _____ until 450 MYA.

aquatic

Animal diversity is influenced by sensory organs, feeding methods, movement, and ________ strategies.

reproductive

Animals can obtain oxygen in water through ____________, _______, or lungs.

Diffusion, gills

Aquatic animals often have ______________ bodies and fins to move efficiently.

Streamlined

The evolution of ________ allowed animals to actively hunt other organisms.

Predation

Sponges belong to the phylum ______

Porifera

Sponges lack ____ ______, although their cells function similarly.

True tissue

Cnidarians have ______ symmetry and _____ germ layers.

Radial, two

Cnidarians have a __________ cavity with a single opening.

gastrovascular

The feeding structure used by many molluscs is called the ________.

Radula

Molluscs have a second body cavity called a ___________.

hemocoel

Cephalopods move using _________ propulsion.

Jet

Cephalopods have a _______ circulatory system, unlike most molluscs.

Closed

All chordates are _________, meaning they develop an anus first.

deuterostomes

The flexible rod that provides support in chordate embryos is the _________.

Notochord

The _______ _______ nerve cord develops into the central nervous system.

Dorsal hollow

Pharyngeal slits in aquatic vertebrates function as _____.

Gills

A defining feature of chordates is a ___________ tail that extends beyond the anus.

Post-anal

One major factor that fueled the Cambrian explosion was an increase in ________ levels.

oxygen

Sharks have skeletons made of _______ instead of bone.

Cartilage

Ray-finned fish have a __________ bladder that helps maintain buoyancy.

Swim

What are the major traits that drive animal diversification?

Sensory organs, feeding strategies, movement, and reproductive strategies.

Why were early animals limited to aquatic environments?

They relied on water for respiration, support, and reproduction.

What adaptations help animals survive in aquatic environments?

Gills/diffusion for oxygen, streamlined bodies for movement, and diverse feeding strategies.

What makes sponges unique compared to other animals?

They lack true tissues and rely on diffusion for metabolic processes.

What is a key feature of cnidarians’ body plan?

A gastrovascular cavity for with a single opening.

How do gastropods feed?

Using a radula to scrape or graze food.

Why do cephalopods have a closed circulatory system?

They require efficient oxygen delivery due to high activity levels.

Well-developed sensory organs have likely played a key role in the success of arthropods. Which of the following activities is NOT improved through well-developed sensory organs?

Formation of zygotes

What are the four key traits of all chordates?

Notochord, pharyngeal slits, dorsal hollow nerve cord, and post-anal tail.

The traits that chordates share as embryos …..

can develop into essential traits for adults or be lost during development

What happens to pharyngeal silts in different organisms?

They become gills in aquatic vertebrates and disappear in adult tetrapods.

What was the Cambrian explosion?

A rapid diversification of animal life where most major animal phyla appeared.

What factors contributed to the Cambrian explosion?

Increased oxygen, environmental changes, new body plans, and the emergence of predators.

What is the advantage of a swim bladder in fish?

It allows fish to maintain buoyancy without expending energy.

If the cells of a sponge are somehow separated and then placed together again, ______.

they will seek each other out and reassemble the entire sponge

The postanal tail is visible in all chordates during ________________.

embryonic stages of the life cycle

why are noncoelomate invertebrates, such as sponges and jellyfish, and noncoelomate worms, evolutionarily important?

They possessed the basic animal body plan from which the body plan of all other animals evolved.

The most morphologically complex class of molluscs is ________. Most members are fast-swimming marine predators with a series of arms and a beak-like ____ that allows them to capture and bite their prey.

cephalopods, jaw

What are the key features of jawed fishes?

Nutritional deficiencies, internal gills, a vertebral column, paired appendages, and single-loop circulation

Most sponges live in what type of habitat?

Marine

Most sponges do not have a definite _______ and do not posses tissues.

symmetry

What differentiates sponges from colonial protists?

Sponges are made of several functionally differentiated cell types

Which phylum has more species than all other phyla combined?

Arthropods

Segmented organisms with jointed legs and a hard exoskeleton composed of chintin belong to the phylum ________.

Arthropod

A hard exoskeleton provides protection against predators; however, it also restricts an animal’s ______.

motion

In arthropods, the hard __________ provides protection and physical support, the jointed ___________ provide flexibility, and the _______ body plan allows specialization of different body parts.

exoskeleton, appendages, segmented

What is the advantage of having jointed appendages?

They can bend.

Arthropods have an ______ circulatory system.

open

In the open circulatory system of arthropods, blood returns to the heart when the heart is _______ by flowing through one-way ______ in the posterior region of the heart.

relaxed, valves

In arthropods, the antennae, mouthparts, and legs are modified ________.

appendages

The evolutionary innovation that first appeared in arthropods and is characteristic of the most successful of all animal groups is that of ________ .

jointed appendages

The passage of an arthropod through stages from egg to adult is

metamorphosis

In what way are a human and a crab similar?

Both have muscles that pull against rigid skeletons.

Frogs and salamanders are members of class ______ within the tetrapods.

Amphibian

________ were the first terrestrial vertebrates

Amphibians

Amphibians have successfully invaded the land, however, most are tied to water for _______.

Reproduction

Why are amphibians tied to water for reproduction?

Reproducing in water prevents eggs from drying out.

What was the biggest challenge to amphibians as they adapted to life on land?

Dehydration