Animals

Question 1

Where did animals evolve from?

Answer 1

likely evolved from sponge-like ancestors (~700-800 Mya)
– oldest known animal fossils include Dickinsonia spp. (558 Mya)
– segmented, blob-like

–analysis of fossils has detected
cholesterol molecules (animal fats)

Question 2

What do we know about animals?

Answer 2

some use sexual reproduction and some use asexual reproduction

Chemoorganoheterotrophs –get energy/carbon from external
dead/living organic matter – primarily phagotrophs (engulfing food)

Multicellular, with NO cell walls(unlike plants and fungi)

Diploid form is dominant –gametes (sperm and egg) are haploid,
(stages are NOT INDEPENDENT, NO ALTERNATION OF GENERATIONS)

have muscle cells (change body shape/form, associated with
movement and feeding)
all animals (except sponges/Placozoa) have nerve cells (neurons),
which allow for system integration across entire organism

Question 3

Five different physical and developmental characteristics to group animals

Answer 3

If the organism has specialized/unique tissues, their type of body symmetry, the type of body cavity/coelom, type of embryological development, and if there is body segmentation

Question 4

Specialized and unique tissues in animals

Answer 4

All animals except sponges/placozoans have specialized tissues (such as msucle, nervous, etc.)

Question 5

Body Symmetry

Answer 5

radial symmetry: no front/back OR left/right; only have endoderm (internal)and ectoderm (external) tissue; (e.g., jellyfish, sea anemones)

bilateral symmetry: have front/back & left/right (all
other animals!); have endoderm, ectoderm, mesoderm
(middle) tissues

Question 6

Body cavity and coelom types

Answer 6

includes an ectoderm (forming the skin and nervous system), a mesoderm (forming muscles and organs), and an endoderm (forms gut)
acoelomate, pseudocoelomate, and coelomate

Question 7

Acoelomate

Answer 7

lack a body cavity/no enclosed body cavity; only have a digestive tract

Question 8

Pseudocoelomate

Answer 8

False Body Cavity –forms between endoderm and mesoderm; no organs in it, filled with fluid or gas (acts as hydroskeleton –helping with body rigidity & movement)

Question 9

Coelomate

Answer 9

True Body Cavity –forms within mesoderm; organ systems & specialized tissues located within coelom

Question 10

Types of Embryiological development

Answer 10

can either be protostome or deuterostome; both have four cell embryo cleavage

Question 11

Protostome Embryological Development

Answer 11

blastopore becomes the mouth; gut cavity develops from mouth to anus(“first mouth”)

Spiral cleavage: New cells form at an angle from underlying cells

all cells have determinate development, cell fate is determined at beginning of development(which could result in death); NO STEM CELLS

Question 12

Deuterostome Embryological Development

Answer 12

blastopore becomes anus; gut cavity develops from anus to mouth(“second mouth”)

Radial cleavage: New cells form directly on top of underlying cells

all cells have indeterminatedevelopment; cell fate is NOT
determined until much later in development; Have STEM CELLS

Question 13

Who are Deuterostomes in Animals? Protostomes?

Answer 13

Phylum Chordata(Vertebrates) and Phylum Echinodermata

EVERYONE ELSE are protostomes

Question 14

Segmentation

Answer 14

1 of 5 ways to group animals

segments allow complex movement, integration
of muscles and skeletal system, and sometimes organ redundancy

In Phylum Annelida, Arthropoda, and Chordata

Other random ones are Onychopora(velvet worms), Tardigrada(water bears), and Kinorhyncha(mud dragons)