BIOL 1108 Edition 1nd Lecture 10 Outline of Last Lecture I Learning Objectives II Portistan Diversity III The Five Kingdom System IV Characteristics of Fungi V Fungal Body VI Saprotrophic Nutrition VII Roles of Fungi VIII Chytrids IX Microsporidia Outline of Current Lecture I Learning Objectives II Metazoan III Ecological roles IV Coral V Phenology VI Protists and the origins of multicellularity Current Lecture I Learning Objectives These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute II III What distinguishes animals from other eukaryotes Why are choanoflagellates thought to be closely related to metazoa What are some of the ecological roles played by metazoa What is the evolutionary history of animals How does the symbiosis between protists and animals affect the marine ecosystem Metazoan a All metazoan are multicellular i Cnidaria 1 The nematocyst is a marvel of biological evolution Triggered by either mechano or chemo reception a barbed stylet shoots out in less than 10 s and delivers toxin to the prey often causing nearly instantaneous death 2 Stings from Box Jellies are generally not fatal if less than a total of 1 meter of sting is received Medicine found the venom causes cells to become porous enough to allow potassium leakage causing hyperkalemia which can lead to cardiovascular collapse and death as quickly as within 2 to 5 minutes 3 Vinegar or any mild acid will not counter act the toxin but it will chemically prevent unfired nematocysts from firing Most victims come out of the water with lots of attached tentacles and mechanical action can cause unfired nematocysts to go off making a bad situation worse 4 Jellyfish kill 15 30 times more people than sharks ii Myxobous 1 Parasitic cnidarians 2 Based on genomic sequence data the Myxozoa cluster as a monophyletic clade within the Cnidaria b All metazoan have a blastula stage of development i Protosome mouth forms first from blastopore ii Deuterostome anus forms first from blastopore 1 Humans are deuterostomes c All metazoan are phagotrophic heterotrophic i Consume food by engulfing food and breaking it down internally rather than spitting enzymes into the environment and sucking in the broken down food Ecological roles Decomposers Consumers Partners in primary production o Zooxanthellae IV V Algal symbionts of marine invertebrates Dinoflagellate protists that form a symbiosis with a number of marine invertebrates Located intracellularly in the coral cells and are surrounded by symbiosome membrane to which lysosomes will not fuse Tridacna giant clam o Not filter feeders o Opens up for photosynthesis Cassiopeia Andromeda o Upside down jellyfish that photosynthesize Parasites Coral Corals produce copious amounts of mucus a complex of mucopolysaccharides Coral mucus is a complex of mucopolysaccharides that are energy rich molecules and play a critical role in the energy balance of coral reefs Forms the base of the food chain for the reef ecosystem Starting with zooxanthellae and some free living algae as the primary producers every other living creature on the coral reef can trace its energy source back to coral snot Mucus functions o when covered in sediment corals shed this layer and thus get all the sediment off of them o the mucus is filled with bacteria their microbiome that like our skin may protect them from pathogenic bacteria and or viruses o If corals are exposed at low tide as is this one it can resist desiccation When stressed corals will eject their Symbiodinium in a process known as bleaching If the symbiosis is not quickly reestablished the reef will die Caused by rising global sea temperatures Threating the survival of coral reef systems loss of many fisheries Phenology Today we recognize four major groups of animals The Parazoa sponges Radiata jellyfish and comb jellies Prostomes most invertebrates and the deuterostomes starfish and vertebrates By the end of the Cambrian radiation all of the major living extant lineages of animals had been established as well as many more that have not made it to the present day These lineages are extinct and have left no living descendants VI One idea is that the development of a triploblastic body type allowed animals to be made in the shape of a tube rather than a flat sheet and there are a great many more body plans that are then possible from a tube rather than a sheet Protists and the origins of multicellularity a Although all animals are multicellular multicellularity is not restricted to the metazoan b Sponges are considered by many to be the simplest form of metazoan life i Haeckel included the sponges among the protists along with choanoflagellates not with the animals 1 Sequence analysis of ESTs from 77 taxa reveals a sister taxon relationship between the choanoflagellates and the metazoa 2 The tandem arrangement of four key mitochondrial genes is identical in all metazoa Choanoflagellates have these four genes in the same order gene synteny but with other additional genes intervening 3 Along with gene sequences gene synteny the order of genes on chromosome can be used to deduce evolutionary relationships ii Sequence similarities in genes that code for cell signaling and cell adhesion proteins suggest a close relationship between sponges and Choanoflagellates 1 A complete sequencing of the genome of the choanoflagellate Monosiga reveals that is shares many cell adhesion and extracellular matrix proteins found in metazoa that are absent in fungi and plants 2 The transition from a colonial choanoflagellate colony to sponge involved the specialization and differentiation of some cells for purposes other than reproduction specialization