Animal Diversity Flashcards
How many species gave been identified
1.3 million extant (living) animals
Defining an animal
~Animals are efficient consumers (predatory behavior or herbervory) of other consumers
~most have adaptations that help them to detect, capture, eat, and digest organisms
Characteristics of animals
- multicellular eukaryotes
- heterotrophs—ingest then digest
- tissues develop form embryonic layers
- cells are supported by structural proteins rather than cell walls— collagen
- NERVOUS TISSUE and MUSCLE TISSUE are unique, defining characteristics of animals
Levels of organization (animals)
The ability to move and conduct nerve impulses underlies many of the adaptations that differentiate animals form other life forms (interpret and react to environmental stimuli)
Reproduction in Animals
SEXUALLY
Or asexual — budding parthenogenesis
Animals zygote development
figure
Development of animals
~Some animals develop directly into adults (primates); however, some animal life cycles involve at least one larval stage
A larva is a sexually immature form of an animal that:
- is morphological distinct from the adult
- typically eats different food
- many live in a different habitat
~METAMORPHOSIS is the transformation that turns the animal into a juvenile that resembles an adult but is not yet sexually mature
(Dramatic anatomical change)
Genes controlling development (animals)
Adult animals vary in morphology, but the genes that control the animal development are similar across a broad range of taxa
- HOMEOBOX GENES regulate the expression of other genes
- HOX GENES control the expression of many genes that influence morphology during embryonic development
(Sponges do not have hox genes)
Origins of multicellular animals
COLONIAL HYPOTHESIS
SYNCYTIAL HYPOTHESIS
figure
Origin of multicellularity requires
Ways for cells to adhere together
Ways for cells to signal each other
~need to identify protist groups that are closely related to animals
morphological and molecular evidence
When comparing a choanoflagellate (monosiga brevicollis) genome to representative animals:
~78 protein domains in M. Brevicollis that were otherwise only known to occur in animals
~genes that encode certain proteins called CADHERINS including:
* play key roles in how animal cells attach to each other * cell-signaling pathways
Steps in the Origin & Diversification of Multicellular Animals
Neoproterozoic Era
(1 billion-542 million years ago) ~the first generally accepted macroscopic fossils of animals date from ~560 MYA *early soft-bodied eukaryotes known as the EDIACARAN BIOTA *molluscs *relatives of sponges *Cnidarians *many have been difficult to identify * possible early animals embryos *early evidence of predation
~organisms generally possessed radial symmetry, some had simple bodies whereas others has many body
segments
KIMBERELLA, DICKINSONIA COSTATA, MAWSONITES SPRIGGI, SPRIGGINA FLOUNDERSI
Paleozoic era
(542-251 Million years ago) ~CAMBRIAN EXPLOSION (535-525 MYA) *fossil evidence- 1/2 of all living animal phyla -arhtropods -chordates -echinoderms ~first large animals with hard, mineralized skeletons ~most fossils are of bilaterians *complete digestive tracts
The decline of ediacaran life-forms as Cambrian life-forms increased
~predator-prey interactions
~increased oxygen leads to increased metabolisms and increased body size
~genetic changes affecting development facilitated evolution of new body forms
After the Cambrian explosion…
Animal diversity continues to increase
~vertebrates emerge as top predators of the marine food web
~arthropods are the first animals to adapt to terrestrial habitats
~vertebrates colonized land ~365 MYA
*diversified into numerous terrestrial groups, only two survive today
