Testing out new features Flashcards
What is the first major branch point in animal phylogeny?
Evolution of tissues
Tissues form when cells work together.
Define symmetry in the context of animals.
Any line through the center of an individual that divides an organism into equal or mirrored halves.
What is asymmetrical?
No lines will divide the organism into equal or mirrored halves.
What is radial symmetry?
Can be split into even halves by slicing at many points that pass through the center.
What is bilateral symmetry?
Can be split into roughly mirrored halves by slicing down the midline.
How do most bilateral animals move through their environment?
Head first, leading with their sensory organs.
What is a body cavity?
A fluid-filled space separating the digestive tract from the body’s outer layer.
What are invertebrates?
Animals without a backbone.
What are vertebrates?
Animals with a backbone.
How many living species are in Phylum Porifera?
5,000 living species.
What do sponges do with nutrient-containing water?
Pores draw nutrient-containing water into a central cavity.
How many living species are in Phylum Cnidaria?
11,000 living species.
Name four examples of Cnidarians.
- Sea anemones
- Hydras
- Corals
- Jellies
What type of tissue helps coordinate body movements in Cnidarians?
Nerve tissue.
How many living species are in Phylum Platyhelminthes?
20,000 living species.
What are acoelomates?
Organisms that have all three embryonic germ layers and the mesoderm fills in the body cavity.
What does hermaphroditic mean?
Organisms have both male and female reproductive organs in one individual.
How many living species are in Phylum Nematoda?
90,000 living species.
What are pseudocoelomates?
Organisms that have all three germ layers and the mesoderm partially lines the body cavity.
How many living species are in Phylum Annelida?
13,000 living species.
What is segmentation?
Division of the body along its length into a series of repeated units.
What are eucoelomates?
Organisms that have all three germ layers and the mesoderm completely lines the body cavity.
How many living species are in Phylum Mollusca?
50,000 living species.
What is a radula?
A saw-like organ that can cut and scrape up food.
How many living species are in Phylum Arthropoda?
Over 1 million living species.
What is an exoskeleton?
A hard skeleton that surrounds the delicate internal organs.
How many living species are in Phylum Echinodermata?
6,000 living species.
What is the function of the water vascular system in echinoderms?
Uses seawater for movement by pushing the water out through the tube feet.
How many living species are in Phylum Chordata?
78,000 living species.
What are pharyngeal slits?
Grooves located just behind the mouth that filters food particles from the water.
What is a notochord?
Flexible rod that gives support along the length of the back.
What is a hollow nerve cord?
Hollow tube that runs along the dorsal surface of the back.
What is a postanal tail?
Extends backward from the anus and is used for locomotion.
Where do lancelets occur?
In shallow marine waters.
What is the difference between lancelets and tunicates regarding chordate characteristics?
Lancelets retain all chordate characteristics in their primitive form; tunicates retain only pharyngeal slits as adults.
What are hagfish known for?
Nearly blind scavengers with an excellent sense of touch and smell.
How do lampreys feed?
By attaching themselves with suckers to the sides of large fish and feeding on blood.
What is the function of a swim bladder in bony fishes?
Helps maintain buoyancy.
What is an operculum?
Protective flap the fish can move to circulate water over the gills.
What is unique about lungfish?
They can gulp air and extract oxygen.
What type of skin do amphibians have?
Smooth, moist skin that is sensitive to pollution.
What are ectothermic organisms?
Organisms with a body temperature that fluctuates with their environment.
What is a characteristic of reptile skin?
Scales that are hardened to provide protection.
What is an amniotic egg?
An egg with a hard, waterproof shell surrounding a fluid-filled sac.
What do birds have that is made of keratin?
Feathers.
What is an endothermic organism?
An organism that maintains its body temperature by its own metabolism.
What do mammary glands produce?
Milk that nourishes newborns.
What is the function of hair in mammals?
Waterproofs the fur and helps retain body heat.
What is unique about monotremes regarding reproduction?
No gestation period; offspring hatch from eggs.
What is the gestation period for marsupials?
4-5 weeks.
How do gestation and lactation times vary?
They vary among placental mammals.
