Marb 435 1st Edition Lecture 8 Outline of Current Lecture Bilateria part 2 and Platyhelminthes 1Current Lecture: All about urineMost aquatic invertebrates are ammonoletic, i.e. produce ammonia• Toxic• Soluble in waterMammals, amphibians, some fish and some molluscs are ureoletic, i.e. produce urea• Non-toxic• Soluble in waterReptiles, insects, some molluscs and some mammals are uricotelic, i.e. produce uric acid• Non-toxic• CrystallizesNephridia- specialized organs that produce urine, are like little kidneysApart from nitrogenous wastes, urine can contain other metabolic wastes, excess ions, spent hormones and toxins ingested with foodSteps of Excretion:1. UltrafiltrationThese 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. Filtration of body fluids (blood, coelomic or interstitial fluids) through a macromolecular filter Results in primary urine Requires two adjacent fluid-filled compartments2. Modification Re-absorption of useful metabolites from primary urine Secretion of specific wastes into primary urine3. Release Discharge of Secondary urine (= final urine) through a nephridioporeExcretory organs in Bilateria1. Protonephridia Occur in animals without a blood vascular system, coelom, or both Usually small-bodied animals with a single body cavity2. Metanephridia Occur in animals with a blood vascular system and a coelomPlatyhelminthes: flat worms Soft-bodied – no cuticle or skeleton No circulatory system Acoelomate, triploblastic and bilaterally symmetrical Hermaphrodites Spermatozoa with two tails No anus – has gastrovascular cavity neoblasts – stem cells that can develop into other cell typesClasses of platyhelminthes that you need to know and things about them!Class Turbellaria- flatworms size range from <1 mm to 60 cm marine freshwater or humid terrestrial habitats ( although most are marine) mostly benthic, few pelagic species use cilia as legs to glide over surfaces but also has body wall musculature for looping or swimmingDiet: o Mostly predators o Some detritivores: dead animals that sink to the bottomo Some herbivores: algae, diatomsFeeding strategies:o Wrapping around prey and covering it with (toxic) mucuso Pinning prey down to substrate with adhesive organso Many species have protrusible pharynx or probosciso Stabbing of prey with penis (has stylet and projects from the mouth!)Class Trematoda- flukesClass Cestoda- tapewormsTerms to know;1. Trichladida- has three branches of gastrovascular cavity2. Polycladida- has many branches of gastrovascular cavity3. Parenchyma- spongy mesodermal tissue between the gut and epidermis4. Gastrovascular cavity- has only one opening, no anus5. Tetrodotoxin (TTX) - a highly toxic chemical that some flatworms can use to poison andconsume their prey. Can also be used by blue ringed octopus, pufferfish, and poison dart frog. (this is important to know)Asexual reproduction: Freshwater planarians have extraordinary regeneration capabilities If head or tail are bisected longitudinally, each half grows a complete new head Even 1/300th of an animal can grow into a complete new worm Totipotent Neoblasts (stem cells) are responsible for regeneration of new tissue Gene responsible for regeneration was recently identified! Same gene might have similar functions in other animalsSexual reproduction: They are all hermaphrodites, meaning they have both male and female structuresMale reproductive structures Paired testes Vas deferens Seminal vesicle PenisFemale reproductive structures Ovaries Oviduct Vitellaria Copulatory bursaMany polyclads use hypodermic insemination and try to stab each other with their penis without getting stabbed themselves. This is known as “penis fencing” and it increases benefits of sperm donation over costs of sperm receipt. Both organisms involved would rather be the male than the female because carrying and producing eggs takes much more work than just inseminating with sperm, which leads to the