Animalia

Question 1

Key Characteristics of Animalia

Answer 1

→ Eukaryotic, cell do not have cell walls
→ Heterotrophs that usually ingest and digest their food
→ Mobile, or have the ability to move, in at least one stage of their life
→ Reproduce sexually and produce and embryo that undergoes stages of development

Question 2

Vertebrates and Invertebrates

Answer 2

Vertebrates: Have a backbone ( 5% of the species in animalia )
↪ All in the phylum Chordata (not all chordates are vertebrates)
↪ Generally large ( some exceptions )
↪ About 60 000 species

Invertebrates: Do not have a backbone ( 95% of species in animalia )
↪ Make up multiple phyla (Approximately 30)
↪ Generally small ( some exceptions )
↪ About 2 000 000 species

Question 3

Characteristics used to classify an animal

Answer 3

1) Levels Organization
2) Number of germ layers
3) Symmetry of body plans
4) Body cavity
5) Digestive system
6) Segmentation
7) Movement
8) Reproduction
9) Nervous System

Great diversity amongst these characteristics

Question 4

Levels of Organization

Answer 4

→ Classified based on the differences between organ tissues and systems
→ Most animals have cells organized into tissues ( except sponges )
↪ Tissues are a group of similar cells that are specialized to do specific tasks
→ Tissues are organized into organs
→ Organs are organized into organ systems

Question 5

Number of Germ Layers

Answer 5

Number of cell layers in the embryo

→ Most animals have three layers
↪ Ectoderm - Outer layer
↪ Mesoderm - Middle layer
↪ Endoderm - Inner Layer
↪ ( exception: Phyla Porifera and Cnidaria)

→ These layers develop into various tissues and systems in early development. In humans…
↪ Ectoderm → skin, nerve tissue, sensory organs
↪ Mesoderm → muscles, blood, kidneys, reproductive organs
↪ Endoderm → lungs, liver, pancreas, bladder, stomach lining

Organisms with all three germ layers are called Triploblastic and organisms with only two germ layers are called diploblastic ( no mesoderm )

Question 6

Symmetry and Body Plans

Answer 6

There are three types

Asymmetrical body plan - body is irregular shape
Radial Symmetry - Can be divided along any plane parallel with the body axis into roughly equal halves
Bilateral Symmetry - Can be divided along one plane, into two equal halves

Question 7

Body Cavity

Answer 7

Coelom: fluid-filled body cavity that provides space for the development and suspension of organs ( kinda like a cushion for the organs ) and organ system (such as the digestive tract)

Animals can be…
→ Coelomate: have a coelom ( has a mesoderm that covers everything )
→ Acoelomate: Don’t have a coelom
→ Pseudocoelomate: Have a coelom but it lacks the cell layers (mesoderm doesn’t cover everything, only body wall)
↪ This trait is analogous and derived independently

Advantages of having a coelom: allows for quick response and movement, and development of complex organs

Question 8

Digestive System

Answer 8

Can have
→ No digestive system
→ Incomplete digestive system
↪ Digestive tube only has one opening ( like a pouch )
→ Complete digestive system
↪ The digestive system has 2 openings, mouth and anus

Animals can be either protostome or deuterostome based on how digestive system develops…

Protostome → Mouth develops before the anus
Deuterostome → Anus develops before mouth

Question 9

Segmentation

Answer 9

Segmentation: The division of the body into repetitive sections or segments

Advantages:
↪ Single segments damaged, but other continue to work
↪ Mobility is more effective

Question 10

Movement

Answer 10

→ Most animals are mobile
→ Some animals are stationary and lives attached to one place (sessile)
↪ At one point in their lives they could move ( Juvenile stage which is between infancy and adulthood ) [ Like sponge have are motile during infancy ]

Question 11

Reproduction

Answer 11

→ All animal produce sexually, some have the ability to reproduce asexually and sexually.
→ Zygotes are either produced by external or internal fertilization
↪ External Reproduction: Gametes combine outside the body
↪ Internal Reproduction: Gametes combine inside the body

Question 12

Nervous System

Answer 12

Some animals have a nervous system while others do not ( there is an increasing level of complexity )

→ Some demonstrate cephalization
↪ This is one nervous tissue becomes concentrated to one side of the organism producing a head region with a brain and sensory organs

Question 13

Symbiosis: Mutualism

Answer 13

Both organisms benefit form the relationship

Question 14

Symbiosis: Commensalism

Answer 14

One organism benefits from the relationship while the other is not harmed (is ‘neutral’)

Question 15

Symbiosis: Predation

Answer 15

One organism feeds on another

Question 16

Symbiosis: Parasitism

Answer 16

One organism, the parasite, causes harm other, the host. The parasite uses the host as a habitat and for resource acquisition

Question 17

Symbiosis: Competition

Answer 17

A contest between organisms for resources, habitat, etc.

Question 18

Phylum: Poriferans

Answer 18

→ Common name: Sponges
→ Representative organisms: Sponges
→ Approximate number of species identified: 5 000
→ Symmetry: Asymmetrical
→ Presence of coelom: No Coelom (Acoelomate)
→ Type of digestive system: No Digestive System
→ Presence of nervous system: No Nervous System
→ Neither Triploblastic nor Diploblastic as it does not have tissue
→ Cellular level of organization

Question 19

Phylum: Cnidarians

Answer 19

→ Common name: Coelenterate
→ Representative organisms: Corals, Hydras, Jellyfish, Sea Anemones, Sea Pens, Sea Whips and Sea Fans.
→ Approximate number of species identified: 11 000
→ Symmetry: Radially symmetrical
→ Presence of coelom: No Coelom (Acoelomate)
→ Type of digestive system: Incomplete Digestive System
→ Presence of nervous system: Have a simple nervous system with nerve cells that interact in a nerve net, without cephalization
→ Diploblastic
→ Tissue level of organization

Question 20

Phylum: Platyhelminthes

Answer 20

→ Common name: Flatworm
→ Representative organisms: Tapeworms, Flatworms
→ Approximate number of species identified: 20 000
→ Symmetry: Bilaterally Symmetrical
→ Presence of coelom: No Coelom (Acoelomate)
→ Type of digestive system: Incomplete Digestive System
→ Presence of nervous system: Have a cephalization and a nervous system
→ Triploblastic
→ Organ level of organization

Question 21

Phylum: Nematodes

Answer 21

→ Common name: Round worm
→ Representative organisms: Roundworm, hookworm, lungworm, pinworm, threadworm, whipworm and eelworm
→ Approximate number of species identified: 30 000
→ Symmetry: Bilaterally Symmetrical
→ Presence of coelom: Pseudocoelomate
→ Type of digestive system: Complete Digestive System (They are Protostomes)
→ Presence of nervous system: Have a cephalization and a nervous system
→ Triploblastic
→ Organ level of organization

Question 22

Phylum: Mollusks

Answer 22

→ Common name: Mollusks
→ Representative organisms: Clams, Cephalopods, Scallops, Snails, Mussels, Oysters, Scallops, Chitons and Shellfish.
→ Approximate number of species identified: 200 000
→ Symmetry: Bilaterally Symmetrical
→ Presence of coelom: Have a Coelom (Coelomate)
→ Type of digestive system: Have a complete digestive system (They are Protostome)
→ Presence of nervous system: Have a nervous system with most mollusks having cephalization
→ Triploblastic
→ Organ level of organization

Question 23

Phylum: Annelids

Answer 23

→ Common name: Segmented Worms
→ Representative organisms: Earthworm, Leechs, Lugworms and Marine worms (Polychaeta)
→ Approximate number of species identified: 20 000
→ Symmetry: Bilateral Symmetry
→ Presence of coelom: Have a Coelom (Coelomate)
→ Type of digestive system: Complete Digestive System (They are Protostomes)
→ Presence of nervous system: Have a nervous system with cephalization
→ Triploblastic
→ Organ level of organization

Question 24

Phylum: Arthropods

Answer 24

→ Common name: Arthropods
→ Representative organisms: Insects, Arachnids, Crabs, Bees, Butterflies and Crustaceans
→ Approximate number of species identified: Somewhere 1.7 to 5-10 million
→ Symmetry: Bilaterally Symmetrical
→ Presence of coelom: Have a Coelom (Coelomate)
→ Type of digestive system: Complete Digestive System (They are Protostomes)
→ Presence of nervous system: Have a nervous system and cephalization
→ Triploblastic
→ Organ level of organization

Question 25

Phylum: Echinoderms

Answer 25

→ Common name: None
→ Representative organisms: Sea Star, Sea urchins, Sea cucumbers, Sea lilies and brittle stars
→ Approximate number of species identified: 7 000
→ Symmetry: Have radial symmetry as adults but bilateral as larvae
→ Presence of coelom: Have a Coelom (Coelomate)
→ Type of digestive system: Complete Digestive System (They are Deuterostomes)
→ Presence of nervous system: Have a nervous system but no cephalization
→ Triploblastic
→ Organ level of organization

Question 26

Phylum: Chordates

Answer 26

→ Common name: None
→ Representative organisms: Mammals, Birds, Amphibians, Reptiles and Fishes
→ Approximate number of species identified: 60 000
→ Symmetry: Bilaterally Symmetrical
→ Presence of coelom: Have a Coelom (Coelomate)
→ Type of digestive system: Complete Digestive System (They are Deuterostomes)
→ Presence of nervous system: Have a nervous system with cephalization
→ Triploblastic
→ Organ level of organization