Lecture 10 Flashcards
What does the life cycle of an animal encompass?
Its embryonic development, birth, growth to maturation, reproduction and death
What is the pattern of development called when newborns are similar to adults in many ways?
Direct development
What is a larva?
An immature life cycle that has a different form to an adult
What is the radical change that butterflies, beetles, bees, moths and flies undergo between larval and adult stages?
Metamorphosis
Give an example of larval and adult stages being specialized for feeding and the other for reproduction/
Adults of most moth species do not eat Butterfly larvae (caterpillars) eat leaves and flowers, adult butterflies eat nectar
Why do animals have different life cycles specialized for feeding and reproduction?
It increases the efficiency with which the animal performs a particular task
What do all life cycles have?
At least one dispersal stage
When do animals that are sessile as adults disperse?
As eggs or larvae- for example, sessile marine animals larva float freely in the plankton
What do animals that live on the sea floor, including polychaete worms and mollusks, have as a common larvae form?
A trochophore
What is the larval form of bilaterally symmetrical marine animals, including crustaceans?
Nauplius
When do animals that are motile as adults disperse>
When they are mature
Give an example of a motile animal dispersing after reaching maturity.
Caterpillar feeds on a single plant- after metamorphosis it may fly and lay eggs on far away plants
What is a trade-off of life cycles?
Characteristics of an animal in any one life cycle may improve its performance in one activity and reduce its performance in another
Where can major trade-offs be seen?
In animal reproduction
What are the trade-offs seen in animal reproduction?
Some animals produce large numbers of small eggs with small energy store,
The larger the energy store, the longer the offspring can develop before it must find its own food/be fed by parents.
What are the two types of young produced by bird species?
Altrical- eggs hatch when young and helpless, must be fed and cared for.
Precocial- incubated eggs for longer, hatchlings are able to forage immediately.
Give an example of precocial hatchlings
Canada Geese hatchlings- Branta canadensis
What do parasite life cycles do?
Evolve to facilitate dispersal and overcome host defenses
Why do parasites have to disperse?
To invade a new host
Because they die when their current host dies
What is the latin name of the broadfish tapeworm?
Diphyllobothrium latum
Explain the complex life cycle of the broadfish tapeworm among hosts.
Free swimming first larval stage is ingested by first intermediate host, copepod
Tapeworm develops in second larval stage and is ingested by first a perch and then a larger fish, before being eaten by mammalian host
What is bilateria?
A large, monophyletic group embracing all animals other than sponges, ctenophores and cnidarians
What traits support monophyly of bilateria?
Bilateral symmetry, three cell layers, presence of at least 7 hox genes
What are the two major categories of bilateria?
Protostomes
Deuterostomes
