Section 29.1 (Exam 2) Flashcards
Diverse Body Plans Allow Animals to Move and Feed in Many Ways
What are some general characteristics of animals?
Multicellular
Movement and nervous systems
Heterotrophic metabolism
Internal digestion
What are the 3 morphological synapomorphies between all animals?
The extracellular matrix is made of collagen and proteoglycans.
They have unique cell junctions.
They have similarities in body plan organization, which is closely related to the shared possession of the hox and other developmental genes.
Which three cell junctions are unique to animals?
Tight junctions, desmosomes, and gap junctions
What theory do the similarities in body plan organization and the shared possession of the hox and other developmental genes support?
That all animals descended from a common ancestor; monophyly
Describe the common ancestor of animals.
May have been a colonial flagellated protist, similar to choanoflagellates, which are similar to multicellular sponges.
Why did the flagellated protists form colonies?
It was more efficient for gathering food.
What are some clues to evolutionary relationships among animal groups?
Fossils
Patterns of embryonic development
Morphology and physiology
Protein structure
Gene sequences
Major animals groups can be differentiated by examining differences in basic __________________.
developmental patterns
Animals groups can be differentiated by their cleavage pattern. What is cleavage?
the first few divisions of a zygote
What is radial cleavage?
Cells divide completely and evenly.
Cells are parallel and perpendicular.
Radially symmetric around central axis
What is spiral cleavage?
Complex, derived form of radial cleavage.
Cells divide diagonally, generally resulting in asymmetry.
Distinct cell layers an also be a way to differentiate between major groups. What are the three groups with a different number of cell layers, how many, and which cell layers do they have?
Monoblastic: 1 cell layer
Diploblastic: 2 cell layers, ectoderm and endoderm
Triploblastic: 3 cell layers, ectoderm mesoderm, and endoderm
After a couple rounds of cleavage, the mass of cells becomes a _________, which is a hollow, tennis ball-shaped structure with fluid inside called __________.
blastula; blastocoel
The blastula undergoes _____________ which forms a ________.
gastrulation; gastrula
Gastrulation is when the blastopore forms. What is a blastopore?
The blastopore is an indent or opening that eventually becomes the mouth or anus.
Triploblastic animals can be divided into two based on the fate of their blastopore. What are the two groups?
Protostomes and deuterostomes
What happens to the blastopore in protostomes?
The mouth develops first, and the anus develops from a second opening.
What happens to the blastopore in deuterostomes?
The anus develops first and the mouth develops later.
What kind of symmetry do protostomes and deuterostomes have?
They are both bilaterians.
All triploblastic animals have ________ symmetry.
bilateral
What are the 5 features related to body plan that vary among animals?
Body symmetry
Body cavity structure
Segmentation
External appendages
Development of nervous system
What is body plan referring to?
The general structure and arrangement of organ systems
Symmetry is present if the animal can be divided into similar halves on at least one plane. If it cannot, it is considered _________. Name some examples of these animals.
asymmetric; placozoans and sponges
If an animal has one main axis around which body parts are arranged, it is considered ___________ symmetric. Name some examples of these animals.
radially; ctenophores, cnidarians, and adult echidnoderms
If an animal can be divided into two mirror image halves on one plane, and generally moves in one direction, it is considered __________ symmetric. Humans are one example of this.
bilaterally
What are the three different axes of bilateral animals?
right and left; anterior and posterior; dorsal and ventral
What is the anterior side?
the head
What is the posterior side?
the rear
What is the dorsal side?
the back
What is the ventral side?
the belly
Bilateral symmetry is correlated with ________________, the concentration of sensory organs and nervous tissue at the anterior end or head.
cephalization
Because the anterior end encounters the environment first, cephalization has been evolutionarily __________. Think about how proximity relates to signals traveling through neurons at quicker speeds.
favored
The structure of the internal fluid-filled body cavity can influence animal ________.
movement
Based on the structure of the fluid cavity, triploblastic animals can be divided into three groups. What are they?
Acoelomates, pseudocoelomates, and coelomates
Describe acoelomates.
No fluid-filled body cavity
Space between gut and body wall is filled with cells called mesenchyme
Movement is by cilia
What is mesenchyme?
connective tissue in acoelomates that fills the body cavity
Describe pseudocoelomates.
Body cavity is a pseudocoel
Muscles are only on the outside
What is pseudocoel?
a fluid-filled space in which organs are suspended
Describe coelomates.
Body cavity called coelom develops within the mesoderm.
Lined with a layer of tissue called peritoneum, which also covers the organs.
More control over movements of fluids in the body cavity.
Name one example of an acoelomate.
flatworm
Name one example of a pseudocoelomate.
roundworm
Name one example of a coelomate.
earthworm
Body cavities can act as ______________, they contain ______________.
hydrostatic skeletons; coelomic fluid
How does a hydrostatic skeleton aid in structure and movement?
pressure of the fluid can provide structural support
when muscles contract, they push fluid to another part of the cavity, which causes that region to expand, allowing for controlled movement
If an animal has both __________ and ____________ muscles, it has greater control over movement.
circular and longitudinal
Segmentation facilitates ____________ of body regions.
specialization
Are segments that are part of the same organism similar or different?
They could be both similar and different
Segmentation is not always apparent ___________.
externally
Segmentation allows animals to alter ____________ and control ____________ precisely.
body shape; movements
External appendages have many uses. Name one of them, and why it is important.
Locomotion is important for finding food, finding mates, and avoiding predators.
Echinoderms have ____ feet to move across the substrate slowly.
tube
Some ______ are highly specialized for rapid, controlled movements, like those of a leopard.
limbs
Arthropods and vertebrates have __________ limbs.
jointed
Limbs were modified into _______ in insects, pterosaurs, birds, and bats.
wings
What are some other uses for appendages aside from locomotion?
Sensing the environment (antennae)
Capturing prey or chewing food (claws and mouth parts)
Reproduction (sperm transfer or egg incubation)
Name two groups of animals that don’t have nervous systems.
sponges and placozoans
___________ are diffuse nervous systems that ctenophores and cnidarians have.
Nerve nets
What does it mean if a nervous system is diffuse?
The neurons are not concentrated like in systems with cephalization. Instead they are evenly distributed across an organism.
Bilaterians have ___________ nervous systems.
central
What is the function of the central nervous system (CNS)?
Coordinates muscle action and movement of body parts.
Processes all sensory information.
Animals are _________________, which means they must expend energy to obtain food from the environment.
heterotrophs
Motile animals can _______________________________ to where food is located.
move through the environment
Sessile animals _________________; they must move the food to themselves.
stay in one place
Name the major feeding strategies of animals.
Filters feeders, predators, herbivores, detritivores, parasites, omnivores
______________ use straining devices to filter small organisms and organic molecule from water.
Filter feeders
Many filter feeders are _________ and aquatic, and rely on water current to bring food to them, or expend energy to move water past their straining devices.
sessile
Motile filter feeders move their filters through the water manually. What are two examples of these?
Baleen whales and flamingoes
____________ eat plants or parts of plants. The plant is usually not killed (unlike prey and predator relationship).
Herbivores
Many kinds of herbivores feed on a ________ type of plant.
single
Because land plants have tissues that are difficult to digest and also defensive chemicals, herbivores have coevolved to have _____________________ for digestion of plant materials.
long, complex guts
___________ capture and subdue other animals.
Predators
Predators have structures such as _________________ and well developed ________________ to detect prey.
sharp teeth and claws; sensory organs
______________ such as humans and raccoons, eat both plants and animals.
Omnivores
_____________ live in or on another animal, the host.
Parasites
Parasites are often much __________ than their host, and the host is not usually killed.
smaller
Parasites often have __________ life cycles.
complex
What are endoparaites?
Endoparasites live inside the host, often have no digestive system, and absorb food directly from host.
What are ectoparasites?
Ectoparasites live on the outside of the host and often have mouthparts to pierce.
What are some examples of endoparasites?
flatworms and tapeworms
Name some examples of ectoparasites.
fleas, ticks, and leeches
________________, or _________________, feed on dead bodies and decompose organic matter (detritus).
Detritivores; decomposers
What are the ecosystem functions of detritivores?
Detritivores return organic material to the environment for other organisms to use
What are some examples of animal detritivores?
earthworms, millipedes, many insects, and crustaceans
