zoology Flashcards
name 6 animalia groups
- eumetazoa
- bilateria
- deuterostomia
- protostomia
- ecdysozoa
- spiralia
what type of cells are choanoflagellates
unicellular eukaryotes
are choanoflagellates free-living, colonial or both
free-living and colonial
what shape collar do choanoflagellates have
funnel-shaped collar
do choanoflagellates reproduce by sexual, asexual reproduction or both
both sexual and asexual reproduction
what was the hypothetical last common ancestor of all animals
ur-metazoan
describe basal metazoans
- asymmetrical or radially symmetrical
- 2 layers of cells
- no organs, some differentiation tissues
what are porifera
sponges
describe proifera
- 2 layers of cells
- no tissues or organs (no nervous/digestive/circulatory systems)
- no symmetry
- ancient lineage
how do the sponges respire and feed
- aquiferous system
- brings water through sponge, pulled through ostia (pores)
- driven across choanoderm (inner layer) by beating choanocyte flagella which pumps large volumes of water at low pressures
- water flows close to cells responsible for food gathering and gas exchange
- excretory + digestive wastes + reproductive products expelled via osculum with out flowing water
what are the sexual reproduction forms for sponges called, describe them
hermaphrodites - eggs + sperm produced at different times preventing self fertilisation
- eggs + sperm usually produced by choanocytes released via aquiferous species
- oviparous (eggs laying species) and viviparous species (release larval forms directly)
- larval ecology split by habitat
how do asexual sponges reproduce (3 ways)
fragmentation - bits of the individual break off
budding - colonial organisms
asexual larvae - not product of eggs n sperm, go through a larval phase before developing
name the 3 classes sponges are put into
- clacarea
- hexactinellida
- demospongiae
where do calcareous sponges reside
in shalllow water
what are calcareous sponges composed of
rayed spicules of calcium carbonate
what other name are hexactinellida sponges
glass sponges
where do hexactinellida sponges reside
deep water
what formation are hexactinellida
silica spicules with 6 rays
what % of living species are demosponges
95%
what formation do demosponges form
silica spicules which is anything but 6-rayed
where are calcareous + coralline demosponges found
shallow water (<200m) needing a firm substrate
where are hexactinellids found
restricted to depths below 200m except for extremely cold environments
where are demosponges found
present at all depths
describe placozoa
- simplest structure of all animals
- 2 layers of cells
- lower surface engulfs organic detritus
- reproduce by asexual budding
describe ctenophora
- radial symmetry
- 2 layers of cells
- unique colloblast cells ->stivky = prey capture, ->sequester stinging cells from jellyfish prey
- swim using cilia
- bioluminescent
describe cnidaria
- diverse group -> coral/jellyfish
- can be sessile (rooted to spot), sedentary (can move but doesn’t really) and pelagic (free floating in water column)
- occur at all depths
- entierly aquatic
- bioluminescent
- symbiotic
what are the key characteristics of cnideria which aren’t shared across all species
- radial symmetry
- diploblastic
- possess cnidae (stinging cells)
- single body cavity
- no nervous system but do have a nerve net
- alteration of generations (asexual polyploid and sexual medusoid)
- ciliate planula larvae (larvae covered in cilia)
what are the 3 types of cnidae
penetrant - pierces + envenoms
glutinant - sticks to prey
volvent - coils around prey
what are the 3 types of cnidae
penetrant - pierces + envenoms
glutinant - sticks to prey
volvent - coils around
true or false
cnidae are single-use
true
when are cnidae used
primarily feeding but secondary as defence
what is the polyploid phase
all classes, sessile phase, can produce asexually
but can bud off medusa to form medusoid phase
what is the medusoid phase
medusozoa only, free swimming, reproduces sexually usually dioecious (female form and male form)
what 2 sub phylum’s can cnidaria be split into
medusozoa - medusoid phase
anthozoa - lacks medusoid phase
what 3 classes are the medusozoa split into
hydrozoa - hydra
scyphozoa - jellyfish
cubozoa - box jellyfish
what 2 classes are anthozoa split into
alcyonaria - sea pens, sea fans, soft corals
zoantharia - sea anemones, hard corals
what are the 4 phylum’s in basal metazoa
- porifera
- placozoa
- ctenophora
- cnidaria
what does eumetazoa mean
the ‘true’ animals excluding the Porifera
what does Coelenterates mean
a paraphyletic group containing the Cnidaria and the Ctenophora - diploblastic
what does Bilateria mean
animals with bilateral symmetry
what does Protostomia mean
animals where the blastopore becomes the mouth - spiral cleavage, schizocoelom
what does Ecdysozoa mean
protostomes that grow by shedding their outer integument
what does Spiralia mean
Protostomes that do not grow via ecdysis
what does Gnathifera mean
Spiralians with complex jaws made from chitin
what does Lophotrochozoa mean
Spiralians which have both a lophophore and a trochophore larva
what does Deuterostomia mean
animals where the blastopore becomes the anus - radial cleavage, enterocoelom
what does Chodata mean
Deuterostomes that possess a notochord, a hollow dorsal nerve cord, an endostyle, pharyngeal slits, and a post-anal tail
what does Ambulacraria mean
Deuterostome group including the echinoderms and hemichordates
what does Apomorphy mean
a new trait that has evolved from an ancestral species
what does blastomere mean
cells that are created when a fertilised egg divides rapidly during cleavage
what does blastopore mean
the point where the blastula invaginates to create the gastrula
what does Blastula mean
early stages of embryonic development, a hollow ball of cells
what does Coelom mean
the fluid-filled body cavity of an animal containing the organs - can be a schizocoelom or an enterocoelom
what does Dioecious mean
having male and female reproductive organs in separate individuals - gonochoric (synonym)
what does Ecdysis mean
shedding of the outer integument, usually as part of growth
what does Enterocoelom mean
a coelom that develops from the wall of the embryonic gut - found in the Deuterostomia
what does gastrula mean
early stage of embryonic development, a 2 layered or 3 layered cup-shaped embryo
what does Hermaphrodite mean
having male and female reproductive organs in the same individual - may be simultaneous or sequential
what does Lophophore mean
a ring-shaped or horseshoe-shaped organ surrounding the mouth which has ciliated tentacles for food capture
what does Metameric mean
an animal whose body is divided into segments that are similar (but not necessarily identical) in structure
what does Monophyletic group mean
a group of organisms that includes a common ancestor and all of its descendants
what does Notochord mean
flexible rod of mesodermal origins found in Chordata - precursor to the vertebrae and important in neural development
what does Paraphyletic group mean
a group of organisms that includes a common ancestor and some but not all of its descendants
what does Polyphyletic group mean
a group of organisms that share similar traits but don’t share a common ancestor
what does Plesiomorphy mean
an ancestral trait present in a particular taxon
what does Protoandry mean
a type of sequential hermaphrodite which begins male and later becomes female
what does Protogyny mean
a type of sequential hermaphrodite which begins female and later becomes male
what does Radial cleavage mean
developmental process where the blastomeres are arranged directly above each other
what does Schizocoelom mean
a coelom that develops from a split in a mesoderm - found in the Protostomia
what does Spiral cleavage mean
developmental process where the blastomeres are arranged in a spiral pattern around the embryo’s axis
what does Synapomorphy mean
a trait present in an ancestral species and shared exclusively by its evolutionary descendants
what does Tagma mean
a grouping of metameric segments into a coherently functional morphological unit (plural tagmata) eg. head, thorax, abdomen
what does taxon mean
a monophyletic group
what does Trochophore larva mean
a planktonic larva that has a roughly spherical body with a band of cilia that allow it to move in a spinning motion
