Exam 3

Question 1

Today there are ~___ million animal species

Answer 1

8

Question 2

Porifera (Sponges)

Answer 2

The earliest groups to have diverged from all other animals.
Lack true tissues: groups of similar cells that act as a functional unit (e.g., muscle, nervous, etc.).
All are aquatic, most are marine.
Sessile (immobile) filter feeders.
Can be very small, or quite massive

Question 3

Animal life began in the ocean with small, soft-bodied species ~__ mya

Answer 3

560

Question 4

All extant (living) animals are descended from a single-celled, eukaryotic ancestor that lived ___ mya.

Answer 4

770

Question 5

Why did the appearance of animals on Earth change the world into a dangerous place for other organisms?

Answer 5

All animals consume organisms (or parts of them) for energy & nutrients.
Most animals are mobile and overwhelm their prey using strength, speed, chemical toxins, or behavioral “tricks” (e.g., camouflage, building traps, etc.)
All but the simplest animals have specialized muscle, nervous & digestive systems that make them highly effective eating machines

Question 6

Cnidarians (Jellies, Sea Anemonies, etc.)

Answer 6

Diverged from all other animals after the sponges.
Considered eumetazoans: true animals, b/c they have true tissues like all other animals.
All are aquatic, most are marine.
Radial body plan: Some are mobile (“medusa”), others are sessile (“polyp”).
All are carnivores with a gastrovascular cavity: one compartment that functions as both mouth and anus, where all digestion occurs. Pre-cursor to a true digestive system.
No brain, but do have simple muscles and nerves.
Types of Cnidarians: Hydrozoa, Scyphozoa, Anthrozoa

Question 7

The Cambrian Explosion

Answer 7

Many large forms of present-day animal Phyla suddenly appear.
The ancestor of modern-day chordates (vertebrates!) and arthropods appear.
The diversity in animal forms that emerged from the Cambrian Explosion consists of relatively few major “body plans.”

Question 8

Body Plan

Answer 8

Particular set of morphological and developmental traits that are integrated into a functional whole – the living animal.

3 important aspects to an animal’s body plan:
1. Symmetry
2. Tissue Organization
3. Body Cavities

Question 9

Radial Symmetry

Answer 9

Body parts arranged around a single main axis that passes through the center of the animal.

Any imaginary slice through the central axis divides the animal into mirror images

Many radial as well as asymmetrical animals are sessile (attached to a substrate) or planktonic (drifting or weakly swimming).

Their symmetry equips them to meet the environment equally well from all sides

Question 10

Bilateral Symmetry

Answer 10

Body parts arranged around two axes of orientation: the head-tail axis, and the dorsal- ventral axis.
Only one imaginary slice divides the animal into mirror-image halves (a right-side and a left-side). Note: many sponges have no actual symmetry
Nearly all bilateral animals have sensory equipment concentrated at the anterior (front) end, including a central nervous system in the head
Enables them to move directionally, and to coordinate complex movements like crawling, burrowing, flying or swimming

Question 11

Tissues

Answer 11

Animal body plans vary with regard to tissue organization.
Tissues can arise from one of 3 different types of germ layers that form during embryonic development:
1. Ectoderm – outermost germ layer; gives rise to the outer covering of the animal and the central nervous system.
2. Endoderm – innermost layer; gives rise to the digestive organs, respiratory organs
3. Mesoderm – in-between layer; gives rise to all the other organs between the outer covering of animal digestive tract (muscles, bones, circulatory system, others)

Question 12

triploblastic

Answer 12

having all 3 germ layers

Question 13

Some animal phyla have no germ layers, some have two, some have all three

Answer 13

Porifera (sponges) have zero (no true tissues)
Cnidarians have two (endoderm + ectoderm)
Bilaterians have three (endo, ecto + mesoderm)

Question 14

Coelom

Answer 14

Fluid-or air-filled space located between the digestive tract and the outer body wall

Develops from the mesoderm

Present in most bilaterians

Functions:
Cushions organs: helps prevent internal injury
Hydrostatic skeleton: for animals with a soft body, non-compressible fluid against which muscles can work
Independent movement: internal organs can move independently of the body

Question 15

Phylogeny

Answer 15

the history of the evolution of a species or group, especially in reference to lines of descent and relationships among groups of organisms

Question 16

Animal Phyla

Answer 16

Diverse animal groups radiated in aquatic environments.
Intense diversification of bilateral animals began about 530 mya.
Most animals are invertebrates. (95-97% of known animal species)
5 Big Takeaways from this phylogeny:
1. Clade Metazoa: All animals share a common ancestor.
2. As the basal group, sponges (Phylum Porifera) are the sister group to all other animals.
3. Clade Eumetazoa: All animals except for sponges are “true animals” because they have tissues.
4. Clade Bilateria: Most animals are bilaterians with the presence of 3 germ layers
5. Most animals are invertebrates (lack a backbone)– there is only one animal Phylum that includes animals with a backbone (Phylum Chordata).

Question 17

Osmoconformers

Answer 17

Internal conditions change to reflect external environment

Benefit: Conforming minimizes energy spent pumping water and ions into/out of the animal’s body.

Downside: Cannot tolerate a wide range of environment conditions, more sensitive to changes

All osmoconformers are marine animals: cartilaginous fishes, most marine inverts.

Question 18

Osmoregulation

Answer 18

Constant internal conditions regardless of external environment

Benefit: Less sensitive to environment changes, can tolerate wider range of conditions.

Downside: Must spend energy
(1) pumping ions against ionic gradient
and/or
(2) conserving or expelling water against osmotic gradient – depends on the environment!

Include most vertebrates whether marine, freshwater or terrestrial

Anything that lives on land is an osmoregulator

Question 19

How do animals acquire the energy and nutrients they need to power their organ systems, grow, and reproduce?

Answer 19

Heterotrophy

Question 20

Nutrition

Answer 20

Food being taken in, taken apart, and taken up by cells.

3 Major Diet Types:
1. Herbivory: Eating plants algae (e.g., cattle, sea slugs, caterpillars, parrotfish)
2. Carnivory: Eating animals (e.g., sea otters, hawks, spiders, hydra)
3. Omnivory: Eating both plants/algae & animals (e.g., humans, crows, crabs, cockroaches)

Question 21

To be an adequate diet, food must satisfy 3 nutritional needs:

Answer 21

1. Chemical energy to fuel cellular processes
2. Organic molecules whose constituent parts can be used as “building blocks” (raw materials) for biosynthesis
3. Essential nutrients that an animal cannot assemble in its own body

Question 22

Ingestion

Answer 22

Food processing begins with ingestion: bringing food into the body

4 main feeding types:
1. Suspension Feeding: Animal filters, captures, or traps food from the surrounding medium.
2. Substrate Feeding: Animal lives in or on its food source
3. Fluid Feeding: Animal seeks nutrient-rich fluid from a living host
4. Bulk Feeding: Animal eats relatively large pieces of food – whole or in pieces; Most common feeding strategy among animals.

Question 23

Absorption (& Assimilation)

Answer 23

Animal cells take up the small molecules that result from digestion.

Sugar monomers, amino acids, fatty acids (etc.) move out of the digestive system and into circulation

Animal circulatory systems deliver absorbed nutrients to cells for use (assimilation). Different animals have different ways of doing this.

Question 24

3 Major Lineages of Mammals

Answer 24

1. Monotremes: egg-laying, produce milk, but lack nipples, only in Australia & New Guinea
2. Marsupials: Offspring born underdeveloped, mature in pouch while nursing from nipple
3. Eutherians: placental mammals, born more developed than marsupials, include primates

Question 25

Invertebrates

Answer 25

Occupy almost every habitat on Earth

Evolution in these varied environments has produced an immense diversity of forms and body sizes

Question 26

Phylum Mollusca

Answer 26

Hugely diverse Phylum that includes > 100,000 species.

3 categories: gastropods, cephalopods, bivalves (surrounded by a shell)

While details may differ, their unsegmented, soft bodies all have 3 main parts:
1. Muscular foot (usu for movement)
2. Visceral mass (contains most of the internal organs)
3. Mantle (fold of tissue that drapes over the visceral mass and secretes a shell (if one is present).

Question 27

Phylum Arthropoda

Answer 27

Most species-rich animal Phylum

Includes insects, crustaceans, horseshoe crabs, spiders, scorpions, barnacles…

1,000,000 arthropods described (most are insects)

1,000,000,000,000,000,000 individuals estimated on Earth!

First animals to colonize land (450 mya)

Members that have:
1. segmented, hard exoskeletons
2. jointed appendages

Question 28

Tetrapods

Answer 28

Animals with digits and limbs (at some point in their development).

What counts as a “limb”: Jointed appendage supported by a bony endoskeleton.

While ray-finned fishes do have a bony skeleton, their appendages (fins) are not not jointed, and are not made of bony endoskeleton (made of thin bony plates).

Includes 4 Classes:
Amphibia
Mammalia
Reptilia
Aves (birds)

Question 29

Tissue Types

Answer 29

The specialized, complex organ systems of (most) animals are built from a limited set of cell and tissue types.

Animal tissues can be grouped into 4 categories:
1. Connective tissue
2. Epithelial tissue
3. Muscle tissue
4. Nervous tissue

Question 30

Nervous Tissue

Answer 30

Receipt, processing, & transmission of information.

Contains 2 major cell types:
1. Neurons: Initiate and transmit electrical impulses to other neurons, muscles, or other cells
2. Glia [clean up neuron’s waste]: Support neurons via nourishment, insulation, replenishment; modulate neuron function.

In many animals, a concentration of nervous tissue forms an information processing center: the brain.

Question 31

Muscle Tissue

Answer 31

Contractive tissue for physical movement of body parts or organs.

Vertebrates have 3 Types, all contain the contractile proteins actin & myosin:
1. Skeletal Muscle: voluntary movements of the skeleton, sensory organs (eyes, ears, etc.)…
2. Cardiac Muscle: beating of the heart
3. Smooth Muscle: pushes forward and/or mixes contents of organs and tubes of the body

Question 32

Epithelial Tissue

Answer 32

Sheets of cells covering the outside of the body, and lining organs and cavities.

Polarized (2 different sides):
1. Apical surface – faces lumen (cavity) or outside of organ, exposed to fluid/air
2. Basal surface – attached to extracellular matrix (basal lamina) that connects to underlying tissue

2 important functions:
1. Barrier against: mechanical injury, foreign pathogens, fluid loss
2. Interfaces with external and internal environments – e.g., in digestive system = absorption of nutrients, secretion of juices/enzymes