1. The Animal Kingdom: A Very Short Introduction, Peter Holland

Question 1

What are animals? 4

Answer 1

1. Animals are multicellular, so amoeba aren’t animals.
2. Can move and sense environment, slime moulds may be an exception here
3. Have epithelial sheets -waterproof. These allow fluid filled areas that are distinct
4. Animals/metazoa are a clade with a common ancestor

Question 2

How did animals originate? 4

Answer 2

1. Animal ancestor was likely to be a ball of flagellated cell, as closed animal ancestor today is choanoflagellate
2. Opisthokonta split to produce animals and fungi
3. May have multicellular life as single-celled can only use flagella for one job at a time - moving or feeding - L. Margulis.
4. May be so cell can eat those connected during famine - M. Kerszberg and L. Wolpert

Question 3

What are phyla? 4

Answer 3

1. Phyla must contain creatures with morphological similarities not present in other animals
2. There are 30-35 phyla
3. Phyla can be added with new species discovery/research, or removed/merged by research
4. Phyla are a good starting point to study as animals within have morphological similarities

Question 4

Describe the coelomata hypothesis. 6

Answer 4

1. Popular phylogenetic tree which uses symmetry and germ layers, cavities, segmentation and early cell divion patterns
2. Non-bilaterian phyla:
   Cnidaria
   Porifera
   Ctenophores
   Placozoa
3. Bilateria have endoderm, medoderm and ectoderm, non-bilaterians (basal phyla) have inner and outer only.
4. Coelomata have coeloms (cavities) at some point in development, some of which disappear. Incl annelids and arthropods, which are also segmented, among others.
5. Acoelomates keep a solid mesoderm with no cavities and may be ancestors or earlier branchers of coelmates
   Pseudocoelmates have rubbish cavities with no surrounding epithelia, may have come between other two

Question 5

Describe the process we use today instead of the coelomata hypothesis. 3

Answer 5

1. Protostome and deuterostome was a popular alternative
2. Segmented annelids and arthropods were previously in one group - Articulata - but 80s research by Raff +co showed this to be incorrect
3. No longer classified by presence of coelom

Question 6

Describe Porifera. 2

Answer 6

1. Respond to touch and chemicals

2. Water moved slowly inside to allow food to become stationary for absorption

Question 7

Describe the Trichoplax. 3

Answer 7

1. Formerly only placozoa
2. Many celled, moved by shape change and cilia underneath
3. Secretes enzymes to feed

Question 8

Describe the Ctenophora (comb jellies). 3

Answer 8

1. Predatory - bump into prey and capture with ‘glue’
2. Have nerve cells and balance organs
3. Comb jellies move via metachronal waves - cilia

Question 9

Describe Cnidaria. 6

Answer 9

1. Biradial symmetry
2. Jellyfish, sea anemones, corals
3. One mouth/anus, surrounded by tentacles with poisonous, stinging cnidocytes
4. Network of nerve cells
5. Include anthozoans, hydrozoans, scyphozoans and cubozoans

Question 10

What are anthozoans? 5

Answer 10

1. Sea anemones
2. Opening at top
3. Mainly staitonary
4. Coral also - are colonial anemone types
5. Bud zooids so colonies are genetically identical

Question 11

What are Hydrozoans? 2

Answer 11

1. Hydra

2. Stinging tentacles surround top mouth

Question 12

What are scyphozoans? 3

Answer 12

1. Jellyfish
2. Downward facing mouth
3. Different tentacles to anthozoans and hydrozoans

Question 13

What are cubozoans? 3

Answer 13

1. Box jellies
2. 24 eyes with lens, iris, retina
3. Dangerous to humans - venom

Question 14

What makes bilaterians different from basal phyla? 2

Answer 14

1. Bilaterians AKA triploblasts have muscles, nerve cords and cephalisation
2. 3D living

Question 15

Talk about the bilaterian body plan. 5

Answer 15

1. Genes determine dorsal and ventral
2. Most animals have ventral nerve cord - chordates are an exception
3. Some developmental toolkit genes eg. Pitx and Hox switch other genes on or off via proteins
4. Nodal and dpp decrete signals for cell-cell communication
5. Less complete toolkits in non-bilaterians

Question 16

Describe annelids. 4

Answer 16

1. Aside from others, Echiura, Sipuncula and Pogonophora are groups of annelid worms
2. Echiura and sipuncula are unsegmented
3. Pogonophora include large tube worms (60-70cm) and giant tube worms (1.5m)
4. Pogonophora have no gut but trophosome organ with chemotrophic bacteria

Question 17

What are plathelminthes and nemerta? 3

Answer 17

1. Platyhelminthes (flatworms) have ripple contractions/cilia for movement depending on size - no muscle blocks
2. Nemertae (ribbon worms) are very slow predators
3. Meters long, milimeters wide.

Question 18

What are molluscs and how did lophotrochozoa get their name? 3

Answer 18

1. Lack of shell can be advantageous - don’t need CaCO3 in environment
2. Trochophore - planktonic larva some lophotrochozoa have
3. Lophophore - feeding structure found in brachiopoda, phoronida, bryozoa

Question 19

What are insects? 4

Answer 19

1. Insects produce uric acid crystals instead of peeing
2. Insects have 2 pairs of wings because not as constrained by evolution as vertebrates
3. Hymenoptera wings adapted for speed and control. They are linked together.
4. Diptera have halteres instead of hind wings - sense organs that allow better flight control

Question 20

Talk about spiders, chelicerates and crustaceans. 2

Answer 20

1. Chelicerates and myriapods invaded land separately
2. It was thought millipedes may have diplosegments due to two legs per segment but actually the segment divide is in a different place on the top and bottom so no longer just simple repeating units

Question 21

What are velvet worms? 2

Answer 21

1. Velvet worms are predators

2. Shoot protein based slime to catch insects and eat whole thing

Question 22

What are moulting worms? 2

Answer 22

1. Nematodes moult

2. High internal fluid posture

Question 23

What are tunicates? 2

Answer 23

1. Larvae are tadpole like

2. Stationary as adults

Question 24

What are some differences between vertebrates and invertebrates? 3

Answer 24

1. Vertebrates are comparatively large
2. Bone is a unique biological tissue - very important
3. Have efficient circulation and protected, elaborate skull

Question 25

What are lampreys and hagfish? 4

Answer 25

1. Lampreys are parasitic and so adults have tidal (in and out) gills and young have unidirectional gills
2. Have a mouth sucker
3. Both lack paired fins
4. Hagfish slime expands and deters predators

Question 26

Name an adaptation that came with the development from lobe fins to legs. 1

Answer 26

1. Flatter snout to snap prey, rather than sucking.

Question 27

Describe axolotls. 2

Answer 27

1. axolotls are amphibians that are about 20cm long, sexually mature tadpoles.
2. No metamorphosis, returned to water from salamanders.

Question 28

Describe reptiles. 3

Answer 28

1. reptiles’ lungs supported by ribs
2. better eggs with multiple membranes
3. one species has women in hot, men in cold, as female body size is more important

Question 29

Describe mammals. 3

Answer 29

1. split at the same time as reptiles
2. many food sources due to occlusion - matching upper and lower teeth
3. Therians - have live birth

Question 30

How are new phyla discovered? 5

Answer 30

1. New species are usually not interesting, but new phyla are
2. unsure if there are any new phyla to be discovered
3. maybe in meiofauna - spaces between sand grains, or the deep ocean
4. New phyla are often a result of new research on old animals
5. often split due to DNA sequencing