Animals Flashcards
What are the major characteristics of animals?
- Consumers (heterotrophs)
- Multicellular
- Cells don’t have cell walls
- Most are able to move
- Diverse in form
- Occupy many different habitats
- Most reproduce sexually
- Have a pattern of embryonic development
- Cells of animals (except sponges) are organized into tissues and tissue layers
What are the five key transitions in animal evolution?
- Tissues
- Symmetry
- Body Cavity
- Various patterns of embryonic development
- Segmentation
Describe the evolution of tissues?
-Parazoa include sponges
They lack defined tissues and organs
They have ability to dedifferentiate and dedifferentiate their cells
-Eumetazoa
All other animals
Have distinct, well defined tissues
Have irreversible differentiation of most cell types
Describe the evolution of symmetry?
- Parazoa have no symmetry but Eumetazoa do
- Radial symmetry: body parts arranged around central axis
- Bilateral symmetry: right and left halves are mirror images
What are the advantages of bilateral symmetry?
- Helps facilitates movement
- The sensory system is in the front of the body
Describe the evolution of a body cavity?
-Eumetazoa produce three germ layers
Outer ectoderm: body coverings and nervous system
Middle mesoderm: skeleton and muscles
Inner endoderm: digestive organs and intestines
-Coelom: space in-between tissues and surrounded my mesoderm
For the evolution of the body cavity what are the three basic kinds of body plans based on the existence of the coelom?
- Acoelomates: no body cavity
- Pseudocoelomates: body cavity between mesoderm and endoderm
- Coelomates: body cavity entirely within mesoderm
Describe the evolution of different patters of development?
Bilaterally symmetrical divided into 2 groups:
- Protostomes: develop mouth first from blastopore then anus (if present) develops later
- Protostomes have spiral cleavage (cells move as dividing)
- Protostomes have determinate development (embryonic cells form specific body regions and if one is removed then development stops)
- Deuterostomes: develop anus first from blastopore then mouth develops later
- Deuterstomes have radial cleavage (cells stay in position as dividing)
- Deuterstomes have indeterminate development (embryonic cells can develop a new individual)
Describe the evolution of segmentation?
Segmentation provides 2 advantages:
- Allows redundant organ systems in adults
- Allows more efficient and flexible movement
What are the two main branches animals are divided into?
-Parazoa: lack symmetry and tissue
-Eumetazoa: have symmetry and tissue
Diploplastic- have 2 germ layers
Triploblastic- have 3 germ layers
What period did an enormous expansion of animal diversity arrive?
Cambrian period
Describe phylum Porifera?
- Sponges (parazoans)
- Marine and freshwater species
- Larval sponges free swimming, adults anchored
- Inner layer: specialized flagellated cells called choanocytes (collar cells)
- Central layer: protein rich matrix called mesohyl
- Filter feeders: choanocyte flagella pull water through pores (intracellular digestion/ digestion occurs in cells)
- Asexual reproduction (fragmentation) and sexual (egg and sperm), larval sponges use cilia to move then settle on substrate to attach and become adults
What two phylum are in phylogeny Diploblasts?
- Cnidaria
- Ctenophora
- Most have radial symmetry and two germ layers
Describe phylum Cnidaria?
- All marine
- Distinct tissues but no organs
- Carnivores
- Body forms: polyp (cylindrical and not moving) and medusa (umbrella shaped and moving) - can alternate between two or be just one
- Reproduce through budding or medusa may produce sexually
- Extracellular digestion
- Have no circulatory, respiratory, excretory systems
- Have specialized cells on epidermis called nematocytes which contains harpoon used for defense or for food
What are the two classes in phylum Cnidarian?
- Cubozoa (box jellyfish)
- Staurozoa (star jellies)
Describe phylum Ctenophora?
- Small phylum includes comb jellies, sea walnuts/ sea gooseberries
- Move with 8 rows of fused cilia
- Capture prey with colloblast (strong adhesive)
- More structurally complex than cnidarians
- Show beginning of many bilateral traits
Describe phylum Platyhelminthes?
- Flatworms that are soft bodied
- Many parasitic
- Protostome
- Acoelomates
- Move with ciliated epithelia cells
- Have developed musculature
What are the three classes under phylum Platyhelminthe?
- Turbellaria
- Trematoda
- Cercomeromorpha
Describe class Turbellaria?
- Free living flatworms
- In freshwater, marine, and terrestrial environments
Describe class Trematoda?
- Flukes
- Parasitic (ecto:outside body, and end:inside body)
Describe class Cheromeromorpha?
- Tapeworms
- Live as parasites in bodies of other animals
- Most live in intestines of vertebrates
Describe phylum Rotifera?
- “Wheel animals”
- Pseudocoelomates
- Spiralia
- Complex internal organs
- Rapidly beating thick cilia at their heads (corona)
- Corona used for transport or funneling food
Describe phylum Mollusca?
- Second most diverse phylum
- Mostly live in salt water
- Wide variety of sizes and body form
- Includes snails, slugs, clams, octopuses, etc
- Can be pests
- Bilaterally symmetrical
- All have open circulatory system except for cephalopods
- Foot of mollusk adapted for movement, attachment, and food capture
- Mantle: epidermis that covers the dorsal side of the body
- Radula: rasping tongue-like organ used for crushing/scraping
What are the four classes of Mollusks?
- Polyplacophora
- Gastropoda
- Bivalia
- Cephalopoda
Describe class Polyplacophora?
- Chitons
- Marine mollusks
- Oval bodies with eight overlapping dorsal calcareous plates
- Most grazing herbivores
Describe class Gastropoda?
- Snails and slugs
- Mainly marine
- Pairs of tentacles with eyes at the end
- During embryonic development they undergo: Torsion (mantle cavity and anus moved from back to front) and coiling (spiral winding of shell)
Describe class Bivalvia?
- Clams, scallops, muscles, oysters
- Have two lateral shells hugest together dorsally
- Mainly sessile filter feeders
- Siphons and cilia keep water circulating
Describe class Cephalopoda?
- Active marine predators
- Foot: serious of arms with suction cups
- Highly developed nervous system
- Many have ink sac
Describe phylum Annelida?
- Annelid worms: always segmented
- Front segments contain special sensory organs
- Ventral nerve cord connects ganglia in each segment with each other and with brain
- Move using coelom
- Closed circulatory system
- Exchange O2 and CO2 through body surfaces
What two classes fall under Annelida?
- Polychaeta
- Clitellata
Describe class Polychaeta?
- Most marine worms
- Differentiated heads
- Have paired parapodia in most segments
- Separate sexes
Describe class Clitellata?
Earthworms -Terrestrial and live underground -No eyes or head -Hermaphroditic: both male and female -Clitellum: secretes mucus that holds worms together during copulation and secretes mucus cocoon Leeches -Mostly in freshwater -Flattened dorsoventrally -No chaetae
Describe phylum Nematoda?
Nematodes: roundworms comprising many species
-Found in freshwater, marine, and terrestrial
-Bilaterally symmetrical and unsegmented
Pseudocoelomates
-Serve as skeleton
-Circular musculature
-No defined circulatory system
-Covered with flexible thick cuticle
-Are Ecdysozoans: molt cuticle four times and exchange oxygen through cuticle
Describe phylum Arthropoda?
- Most successful animals
- 80% are insects
- Have join appendages
- Have exoskeleton made of secreted chitin and protein
- Segmented bodies (like crickets)
- Open circulatory system
- Compound eyes (composed of ind. visual units) but others have simple, basic eyes (ocelli) which have single lens and distinguish light from dark
- Undergo ecdysis (molting)
What are the four classes of Arthropoda?
- Chelicerata
- Myriapoda
- Crustacea
- Insecta
Describe class Chelicerate?
- Spiders, scorpions, horseshoe crabs, ticks, mites
- Body divided into two main tagmata (fused segments): Chelicerae (appendages and most in front of face ex. pinchers) and Pedipalps (posterior to chelicerae ex. legs, used in reproduction, pincers, sensors)
Describe class Myriapoda?
Centipedes (possibly poisonous) -One leg pair on each segment -Carnivores Millipedes -2 legs on some or all segments -Mainly herbivores
Describe class Crustacea?
- Primarily aquatic (crabs, shrimp, lobster, barnacles)
- 3 Tagmata but front two may fuse
- Two pairs of antennae, 3 pairs of appendages
- Most appendages biramous (branch into two parts)
- Mandibles evolved from pair of limbs that took on chewing function
- Separate sexes
Describe class Insecta?
- Insects
- Largest group of animals
- Mainly terrestrial
- 3 body regions: head (compound eyes, antenna), thorax (3 pairs legs, wings), abdomen (organs)
- Complex digestive tract (takes place in stomach)
- Undergo metamorphosis: Simple (look like adult) or Complete (transform)
Describe phylum Echinodermata?
- Ancient group of marine animals
- Deuterostomes
- Endoskeleton
- Starfish
- Pentaradial symmetry
- Exoskeleton made of calcium plates called ossicles
- Contain mutable collagenous tissue
- Water vascular system aids in moving, feeding, circulation
- Sexual and external reproduction but asexual through splitting
Describe Chordates?
- Birds
- Five features:
1) Nerve cord
2) Notochord
3) Pharyngeal slits (gills)
4) Postanal tail
5) Endostyle
What are the three subphyla of Chordates?
- Cephalochordata
- Urochordata
- Vertebrata
Describe Cephalochordata?
- First chordates
- Show typical segmentation
- No anterior sense organs or brain
- Feed on plankton using cilia that generate currents
Describe Urochordata?
- Tunicates
- Secrete cellulose tunic that surrounds animal
- Marine
- Larvae tadpole like
- Adults are immobile
Describe Vertebrata?
- Vertebrates: Chordates with spinal column
- Have vertebral column and head (non vertebrates don’t have this)
- Have internal organs and closed circulatory system
- Endoskeleton (made of cartilage or bone)
Describe Fishes?
- Most diverse vertebrate group
- Have vertebral column
- Have jaws and paired appendages
- Have internal gills
- Have single loop blood circulation
- Have nutritional deficiencies
Describe the history of fishes?
- First fish had no jaws
- Cyclostomata: Jawless fish that included lampreys and hagfish
- First vertebrates to develop teeth (evolved from scales)
- Have lateral line system: series of sensory organs that detect water pressure changes
- Acanthodii (spiny fishes)
- Placodermi (armored fishes)
- Bony fish are most species rich of all vertebrates
- Swim bladdar: gas filled sac that allows body fish to regulate buoyancy
- Gill cover: hard plate covers gills and moves to keep water flowing through gills
What are the two major groups of bony fish?
- Class Actinopterygii (no muscle in fin) ray finned fishes
- Class Sarcopterygil (fleshy and muscular lobe) lobe finned fishes
Describe class Amphibia?
- Damped skinned vertebrates
- First vertebrates to walk on land
- Adapted legs, lungs, redesigned heart, reproduction in H2O
- Evolved from lobe finned fish
- Redesigned circulation (2 to 3 chambered heart
What are Amniotes?
- Animals with amniotic egg (protected by shell)
- Has four membranes
- Water tight
- Internal fertilization
Describe class Reptilia?
- Have amniotic egg
- Dry skin prevents H2O loss
- Thoracic breathing
- Better circulation
Describe Archosauria?
- First bipedal vertebrates were dinosauria
- Complex parental care
- 4 chambered heart
- 2 groups today: crocodylia and aves
Describe class Aves?
- Direct descendent to carnivorous dinosaures
- Most diverse of all terrestrial vertebrates
- Feathered
- Hollow and thin bones
- Efficient respiration
- Efficient circulation
- Endothermy (body temp. allows higher metabolic rate)
Describe Mammals?
- Hair
- Mammary glands
- Endothermy: depends on more efficient circulation and respiration
What are the three orders in class Mammalia?
- Monotremes
- Marsupials
- Placental Mammals
Describe order Monotremes?
- Amniotic eggs
- Have single opening, cloaca, for digestion and reproductive tracts
Describe order Marsupial?
- Embryo (nourished by yolk and born underdeveloped, like kangaroo)
- After birth crawls into pouch and latches onto nipple
Describe order Placental Mammals?
- Most living mammals
- Placenta
