animals meaning bearer organisms bodies pores channels allowing water consisting like thin layers cells cells transform types migrate main cell layers process nervous digestive systems instead rely maintaining constant water flow bodies obtain food oxygen remove overview similar animals lack cell walls produce sperm cells unlike animals lack true tissues organs body symmetry shapes bodies adapted efficiency water flow central cavity deposits nutrients leaves hole called internal skeletons calcium dioxide aquatic animals freshwater species great majority marine salt water species ranging tidal zones depths exceeding approximately known species feed bacteria food particles water host micro organisms alliances produce food oxygen consume species live food poor environments prey mainly small crustaceans species use sexual reproduction releasing sperm cells water species released retained mother eggs form larvae swim search places settle known fragments broken works fragments include right types cells species reproduce conditions deteriorate example temperatures drop freshwater species marine ones produce survival pods cells remain dormant conditions improve form completely new skeletons parents functions skeleton soft hard surfaces rocks commonly mineral fibers use species species calcium constitute known species including freshwater ones widest range habitats calcium species calcium restricted relatively shallow marine waters production calcium easiest fragile glass restricted polar regions ocean depths predators rare fossils types found rocks dated million years ago addition fossils common rocks million years ago regarded type single resemble cells drive water flow systems capture food phylogenetic studies molecules morphological evidence suggest sister group rest animals studies shown form group words include descendants common ancestor recent phylogenetic analyses suggest sister group rest animals species entirely soft skeletons hard elements humans thousands years purposes including cleaning tools 1950s heavily industry collapsed like materials synthetic microscopic researched possible sources treating wide range diseases observed tools foraging distinguishing features constitute defined animals water intake outlet openings connected chambers lined cells whip like lost water flow systems known living bodies types cells bodies change type like etc unlike known bodies consist non living like mass main layers cells simple nervous systems cell layers bound internal connections mounted basement membrane thin mat known basal nervous systems middle like layers large varied populations cells types cells outer layers middle layer change functions basic structure cell types body hollow held shape like substance mainly reinforced dense network fibers inner surface covered cells cylindrical conical surrounding wave like motion whip like drives water body channels leading interior controlled tube like form inlet plate like cells form single layered external skin parts covered digest food particles large enter base animal responsible types cell live like cells slowly type producing cell cells form reproductive cells little spines form skeletons species provide defense predators addition instead form thick material muscle cells conduct signals cause parts animal contract grey cells act equivalent immune system like cells words capable transformation type cell important roles feeding clearing debris block glass glass present distinctive variation basic plan form like framework rods living tissue suspended like contains cell types tissue ways like cells share single external membrane like single cell multiple absent minimal fluid fills interiors cells organized rivers transport organs cells substances instead known form bell shaped chambers water enters chambers lined collar bodies consisting collar nucleus motion water passages open ends bell shaped chambers types cells single nucleus membrane connected single nucleus cells main bridges build multiple glass larvae connected tissues bridges connections far found adults simply reflect difficulty investigating small scale features bridges controlled junctions apparently permit substances pass blocking water flow body structures work like chimneys water little mouth ambient currents faster effect produce principle work free control water flow combinations wholly partially closing intake pores varying beat shut lot sand water layers resemble complex animals bound tightly cell cell connections basal thin sheet underneath flexibility layers modeling allow animals adjust shapes lives maximum advantage local water currents simplest body structure tube shape known severely limits size animal body structure characterized stalk like surrounded single layer simply scaled ratio volume surface area increases surface increases square length width volume increases cube tissue needs food oxygen determined volume pumping capacity supplies food oxygen depends area covered seldom exceed diameter overcome limitation adopting structure body wall inner pockets lined connect outer pockets increase number pumping capacity enables grow centimeters diameter pattern pumping capacity filling interior completely contains network chambers lined connected water outlet tubes grow diameter fact growth direction increases number chambers enables wider range forms example shapes follow surfaces attach freshwater shallow water marine bodies networks water passages glass similar structure types structure cross section area lined regions greater intake outlet channels makes flow slower near makes easier trap food particles example small centimetres tall diameter water enters intake canals minute million chambers combined diameter greater canals water flow chambers hour making easy capture food water expelled single second fast carry waste products distance away skeleton skeleton fairly rigid structure animal joints functions skeleton soft hard surfaces rocks commonly mineral fibers calcium vary shape simple rods dimensional stars rays produced cells separate connected joints fused lie completely outside organic components example hard massive calcium organic matter forms thin layer chambers pits mineral form animals skins classes traditionally distributed classes glass studies shown group thought belong actually separated recently recognized fourth class divided classes mainly according composition skeletons vital functions movement adult fundamentally animals marine freshwater species sea bed speeds day result like movements cells species contract bodies close juveniles drift swim freely adults stationary feeding distinct respiratory digestive systems instead water flow system supports functions filter food particles water flowing particles larger enter consume internal particles trapped outer inner ends particles consumed partially walls bacteria sized particles pass caught consumed smallest particles far common typically capture food supply transport food packaged cells directly digest food species internal fibers function tracks use nutrient carrying tracks objects claimed glass live nutrients dissolved sea water study found evidence concluded extract bacteria micro organisms water efficiently process suspended sediment grains extract prey collar bodies digest food distribute wrapped transported motor molecules run cells absorb oxygen water cells water flows body carbon dioxide waste products remove mineral particles threaten block transport generally dump outgoing water current species incorporate skeletons species live waters supply food particles poor prey crustaceans small animals far species discovered belong family members cases little known actually capture prey species thought use sticky threads hooked live deep waters development deep ocean exploration techniques expected lead discovery species found mediterranean caves depths alongside usual filter feeding cave dwelling predators capture crustaceans long fine threads digest threads course days return normal shape evidence use venom known completely lost water flow system genus uses highly modified water flow system balloon like structures capturing prey freshwater host green algae cells benefit nutrients produced algae marine species host organisms commonly cases form total mass living tissue gain energy supply micro organisms team reported conduct light live host organisms common waters relatively poor supplies food particles shapes maximize sunlight collect recently discovered lives near hosts eating bacteria immune system complex immune systems animals reject species accept members species marine species gray cells play leading role rejection foreign material invaded produce chemical stops movement cells affected area preventing internal transport systems intrusion grey cells concentrate area release kill cells area immune system stay activated state weeks reproduction methods reproduction producing fragments detached currents waves use mobility attach suitable surface rebuild small functional course days capabilities enable fine cloth fragment contains produce produce cell types species reproduce survival pods marine freshwater species produce thousands dying mainly freshwater species regularly produce autumn wrapping shells reinforced round clusters nutrients freshwater include dormant state survive cold drying lack oxygen extreme variations freshwater revive temperature drops stays cold months reaches normal level round outside cluster transform membrane shell bursts cluster cells slowly emerges remaining transform cell types needed functioning species different individuals join forces form retained parent spring difficult tell old revived sexual function sexes simultaneously reproductive organs sperm produced entire chambers sink form eggs formed transformation species egg generally yolk consuming nurse cells spawning sperm burst expelled contact species water flow carries instead form carry sperm eggs cases carrier cargo species release eggs water retain eggs hatch types larvae balls cells outer layer cells enable larvae swimming days larvae sink crawl find place settle cells transform types appropriate locations miniature adult glass embryos start dividing separate cells cells formed rapidly transform larvae externally band round middle use movement internally typical glass structure like main multiple collar bodies center larvae leave parents bodies life cycle temperate regions live years tropical species deep ocean ones live years grow year rate constant specimens wide years old start sexual reproduction weeks old wait years old coordination activities adult lack kind nervous tissue species ability perform movements coordinated bodies mainly water channels excess sediment substances cause species contract independently rest body contract order reduce area vulnerable attack predators cases fused example large waves slowly coordinated twins coordinating mechanism unknown involve chemicals similar glass rapidly transmit electrical parts use halt motion incoming water contains excessive sediment thought responsible closing signals different parts body contain genes similar contain recipe post density important signal receiving structure animals genes activated cells appear larvae provide sensory capability larvae swimming raises questions cells represent predecessors true evidence ancestors true lost adapted lifestyle ecology habitats worldwide distribution living wide range ocean habitats polar regions tropics live quiet clear waters sediment stirred waves currents block pores making difficult feed breathe greatest numbers usually found firm surfaces rocks attach soft sediment means root like base abundant diverse temperate waters tropical waters possibly organisms prey abundant tropical waters glass common polar waters depths temperate tropical seas construction enables extract food resource poor waters minimum effort abundant diverse shallower non polar waters different classes live different ranges habitat primary producers produce times oxygen consume organic matter consume contributions habitats resources significant australia great barrier reef relatively minor caribbean defenses shed forming dense carpet meters deep keeps away prey produce prevent organisms sea growing near making effective competitors living space examples includes species caribbean fire cause severe humans handle turtles fish feed mainly said produce chemical defenses predators experiment showed relationship chemicals produced taste fish diminish chemical defenses predation fish help spread fragments glass produce toxic chemicals live deep water predators rare predation flies known flies specialist predators freshwater female lays eggs vegetation water larvae hatch drop water seek feed use elongated pierce suck larvae species surface refuge internal fully grown larvae leave water spin caribbean chicken liver kill coral allowing grow coral skeletons especially family use substances tunnel rocks shells dead remove year reefs creating visible low tide level diseases caribbean genus suffer red band syndrome causes develop colored bands adjacent bands tissue completely branches disease appears impacts approximately percent reefs colored bands caused unknown organism actually causes disease collaboration organisms addition hosting noted wide range collaborations organisms relatively large common rocky surfaces extended range meadows letting surrounded local protect return higher positions away sea floor sediment genus form colonies shrimp species inhabits different species making diverse genera specifically utilizes food source defense shrimp predators individuals inhabit single feeding larger particles collect filters ocean feed evolutionary history fossil record stable derivative said produced true animals thought animals closest single relatives team scientists examined genes species concluded species produce investigation wider range necessary order prove fossil produced previous publication reported traces chemical ancient rocks dating million years ago recent research accurately dated rock series revealed appear end approximately million years ago analysis reveal convincing evidence ancient pre dating globally extensive glacial episode million years ago sources marine algae origin molecular suggest existed explosion life like absent fossil record report exists rocks dated million years ago appears unlikely based reference preserved fossil million years ago period found formation fossils include internal cavity classified fossils glass found million years ago rocks australia china early mexico belonging genus evidence fusion smaller form single large calcium found early rocks million years ago australia probable found early fauna million years ago freshwater appear younger earliest known fossils date period million years ago modern remains type common types skeletons composed relatively soft earliest known early classify type common period million years ago apparently died end million years ago family tree 1990s widely regarded group words descended common ancestor sister group multi animals form group hand 1990s analyses revived idea animals nearest evolutionary relatives single organisms similar imply evolved like ancestors like ancestors given rise modern non members analyses concluded complex closely related particular groups rest conclusions imply common ancestor direct ancestor study based comparisons dna concluded fundamental division glass rest closely related calcium types analysis based comparisons based mainly comparison concluded glass closely related turn closely related evidence links sub group comparison nuclear dna excluding glass concluded closely related closest evolutionary groups bag like animals fossils found rocks sperm share features lack layers cells bound attachment carpet like basal membrane composed mainly type form found fibers reinforce similar type analyses described concluded closest ancestors words multi animals including complex groups comparison genes genera ranging fungi humans including species suggested basal lineage included sample correct modern developed complex structures independently ancestors complex known drastically simplified forms study recommended analyses wider range simple results analysis published suggest return previous view family trees constructed combination available data morphological developmental molecular concluded fact group form sister group common fossils rocks early million years ago found late suggested produced algae completely separate animals completely separate kingdom life labeled 1990s regarded distinctive group difficult fit classifications complex animals analysis concluded closely related grounds detailed structure armor plates similar fibers protein modern analysis concluded intermediate complex animals reasons skins thicker tightly connected detailed analysis concluded similar mobile animals looked like chain mail fossils found rocks early mid correct create dilemma extremely unlikely totally unrelated organisms developed similar independently huge difference structures bodies makes hard closely related taxonomy classified kinds animals belonging order class mistakenly identified genus plants order algae long time assigned separate animals separate formed rest kingdom classified higher animals evolved divided classes mainly according composition skeletons glass largest rays individual fused main components bodies large numbers cell share single external membrane skeletons form calcium form separate large masses cells single nucleus membrane fibers soft tissues massive external skeletons form calcium cells single nucleus membrane known fossils period 1970s massive calcium skeletons assigned separate class known 1980s found members far scientific publications identified species glass species rest types habitat vertical rock cave walls galleries rock coral investigated little shallow seas use report described use tool western australia attach marine presumably protect searching food sandy sea behavior known observed bay exclusively shown females study concluded mothers teach behavior daughters users closely related suggesting fairly recent innovation humans skeleton calcium genera rough uses genera soft entirely skeletons early europeans soft purposes including helmets portable drinking municipal water filters invention synthetic cleaning tools mid-20th century fishing brought animals industry close extinction diving objects like textures substances derived synthetic include personal household cleaning tools breast typical materials foam foam frequently foam spelled commonly sold use kitchen shower derived animal mainly skeleton compounds medicinal potential presence chemicals control bacteria fungi active compounds lacking protective shell means escape evolved variety unusual compounds class acid derivatives called members family found anti cancer anti anti fungal properties example isolated shown potential cells
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