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Department
Biology (Sci)
Course
BIOL 111
Professor
Multiple
Semester
Fall

Description
Bio 111 Alanna Houston October 18, 2007 SPONGES Asexual Reproduction: - Fragmentation: o Not self-induced o Waves, predators - Budding: o Clone of parent Sexual Reproduction: - Hermaphroditic o Sperm and eggs develop inside single cells o Broadcast sperm o Filter in different sperm o Eggs fertilized, develop in jelly layer (mesohyl) o Larvae released o Settle on suitable substrate o Develop in sessile adult Sponge Origins: - Evolved ~ 700 MYA - Ancestor – coanoflagellate (protists) cells are similar to choanocytes of modern sponges Limitations of Sponges: - Very successful group, but… - Unable to feed on larger prey than choanocytes o Digestion is intracellular - Unable to achieve high level organization or coordination between body parts o Cellular level of organization o No tissues etc. cannot respond to stimulus and do not have muscles to move When in time first displayed a gut: C (look at phylogeny) Evolutionary innovations: - Gut o Enables extracellular digestion - Tissues o Enable body organization ANIMALS Which is not a characteristic of animals: - D: a haploid multicellular life stage - Their multicellular life stage is diploid Characteristics of Animals: - Eukaryotic - Heterotrophic Bio 111 Alanna Houston - No cell walls - Motile at some life stage - Multicellular - Have tissues - Life cycle mostly diploid - Unique embryonic development Embryonic Development - Embryo: a young animal or plant contained within a protective structure (seed, egg or uterus) - Zygote: multicellular organism - 2 major processes during embryonic development o Cleavage: cell division – process forming many cells from one cell o Gastrulation: infolding – process forming embryonic tissue layers (2-3) from one layer of cells o o Zygote – cleavage  morula (solid ball)  blastula (hollow ball) – Gastrulation  early gastrula and blastopore (opening)  late gastrula forming a higher bigger blastopore o Bio 111 Alanna Houston - Gastrula: o Layers of embryonic cells = germ layers o Germ layers: ectoderm (epidermis, nervous system) – outer layer, endoderm (lining of digestive and respiratory systems) – inner layer - Animals with two germ layers are diploblastic (simpler animals) o 3rs layer is called mesoderm (inside) – most internal organs: muscles, skeletal system, heart, stomach - Animals with three germ layers are triploblastic (us) - Blastopore turns into mouth of anus - Archenteron is the digestive space (gut cavity – one opening) - A tract has an in and an out whereas a cavity only has one opening - - Triploblasts start after cnidarians CNIDARIANS Challenge One: Obtaining Energy - Heterotrophic - Sometimes sessile during life - Multicellular – how get nutrients to all cells? (Cells have to be small) Must be another way other than simple diffusion - Capture food with cnidocytes (stinging cells) Bio 111 Alanna Houston o o Fastest most powerful cellular process o Can penetrate carapace of crab shell - Predators - Corals, Anemones, Sea fans, - Coral Reefs are in clear places (not much nutrients – symbiosis with photoautotroph) Body Plan: - Sac of cells - - Gastrodermis (from endoderm – lines digestive cavity) - Gastrovascular cavity (blind gut – from archenterons) - Mouth (from blastopore) - Epidermis (from ectoderm) - Mesoglea – jelly non-living layer (forms hydrostatic skeleton) - Diploblastic Two Forms: - Polyp o Sessile o Sea anemone - Medusa o Motile o Jellyfish Bio 111 Alanna Houston - Cnidarian Diversity: - Scyphozoans o Medusa is dominant, polyp is reduced o Jellyfish o Cup animals o Large amount of mesoglea o All marine o Example: Cassiopeia  Upside down jelly  Symbiotic algae – use algae to supplement O2  Tolerates low O2 conditions - Anthozoans o Polyp is dominant, no medusa o Coral
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