Invertebrates Domain Eukarya Kingdom Animalia The Metazoans
Evoln of Animals Animals of Kingdom Animalia are multicellular euakaryotic heterotrophs that ingest their food Animals have the diploid life cycle and usually reproduce sexually
Muscle and Nerve Tissues characterize animals Enables animals to 1) search actively for their food and 2) prey on other organisms
Animals are monophyletic Both invertebrates and vertebrates can trace their ancestry to the same ancestor Adult vertebrates have a spinal cord (backbone) Invertebrates do not have a backbone
Ancestry of Animals The colonial flagellate hypothesis states that animals are descended from an ancestor that resembled a hollow spherical colony of flagellated cells
Colonial flagellate hypothesis implies that radial symmetry preceded bilateral symmetry in the history of animals
Any longitudinal cut produces two identical halves Radial Symmetry
Bilateral Symmetry Only one longitudinal cut yields two identical halves
Remember the Choanoflagellate?
The choanoflagellates (collared flagellates) resemble the last unicellular ancestor of living animals, and molecular data illustrates that they are the closest living relatives of animals As water moves through the microvilli, they engulf bacteria and debris from the water
Phylogenetic Tree of Animals -Cladogram- Based on molecular and morphological data The more closely related two organisms are, the more rrna nucleotide sequences they will have in common It s all genetic and chemical
Morphological Data Asymmetry Radial Symmetry Bilateral Symmetry
Asymmetry There is no particular body shape (e.g., sponges)
Radial Symmetry Body parts arranged around an axis, like spokes of a wheel (e.g., starfish) May be sessile attached to a substrate or less motile Enables the animal to reach out in all directions from one center
Bilateral Symmetry Body plan having a right and left, or complementary halves Only one longitudinal cut down the center produces mirror halves Tend to be active Have anterior (front) and posterior (back) ends Development of head to localize the brain and sensory organs at the anterior end (Cephalization)
Embryonic Development The first three tissue layers are called germ layers. They give rise to the organs and organ systems of complex animals
Diploblastic Animals with two tissue layers (ectoderm and endoderm) as embryos
Triploblastic Animals that develop further and have all three tissue layers (ectoderm, mesoderm, and endoderm) as embryos Can be further divided into protostomes or deuterostomes A coelom forms by the splitting of the mesoderm.
Protostomes exhibit the following events during embryological development Spiral cleavage in which the cells divide w/o an in size Fate of cells is fixed each contributes to development in only one particular way blastopore is associated w/ the mouth A coelom forms by splitting of the mesoderm, which has arisen from cells near the blastopore
A body cavity Coelom Lies between the gut and body wall and has a lining (the peritoneum) derived from the mesoderm Organs that developed w/in this cavity are cushioned and protected
Deuterostomes exhibit the following events during embryological development Radial cleavage - the new daughter cells sit atop the previous cells Fate of cells is indeterminate Blastopore is associated with the anus, mouth appears later Coelom forms by the fusion of mesodermal pouches from the primitive gut
Body Cavities - Acoelomate epidermis gut cavity no body cavity; region between gut and body wall packed with organs Fig. 25-6, p.406
Body Cavities - Pseudocoelomate epidermis gut cavity unlined body cavity (pseudocoel) around gut Fig. 25-6, p.406
Body Cavities - Coelom gut cavity lined body cavity (coelom) peritoneum Fig. 25-6, p.406
Phylum Porifera The Sponges
No symmetry No tissues Cells line all body surfaces but don t form distinct tissues No organs Aquatic Sessile Filter feeders water enters through tiny pores and exits through one or more large openings
Collar cells trap food Cells engulf bacteria or other organic debris Collar cells release some of it to amoeba-like cells that process food and carry out other tasks that benefit the sponge
Water injected with fluorescien dye to watch the filtering process
Sponge Skeleton All sponges have fibers made of spongin a protein that gives the sponge its flexibility The endoskeleton contains spicules tiny needle shaped structures with 1-6 rays
Sponge Predators Sea Slugs Very few b/c of spicules and production of foul smelling and toxic substances
Asexual Reproduction - Budding Small buds or pieces break away and grow into new sponges Can produce large colonies Fragmentation Production of Gemmules - encapsulated amoebocytes
Sexual Reproduction Eggs and sperm are released into the central cavity Zygote develops into a ciliated larva free living, sexually immature stage of animal development Larvae are flagellated, can swim briefly until settle in suitable substrate
water out glasslike structural elements central cavity amoeboid cell pore semifluid matrix flattened surface cells water in flagellum microvilli nucleus Stepped Art Fig. 25-10, p.409
Fig. 25-9d, p.408
The Jellies
Phylum Ctenophora The Comb Jellies The largest animals propelled by beating cilia Range in size from a few cm to 1.5 m in length Most of their body is jelly-like material called mesoglea Long tentacles covered with sticky filaments or an entire body covered by sticky mucus captures prey
Cnidarians Tubular or bell-shaped Can be marine, freshwater or brackish forms Gastrovascular cavity digests food, circulates nutrients and serves as supportive hydrostatic skeleton Phylum Cnidaria
Phylum Cnidaria Only animals that produce nematocysts Nerve net Hydrostatic skeleton Saclike gut capsule s lid at free surface of epidermal cell trigger barbed thread inside capsule nematocyst Fig. 25-13, p.410
Have cnidocytes specialized cells containing nematocysts The nematocyst is a fluid-filled capsule containing a long, spirally coiled hollow thread When the trigger of cnidocyte is touched, the nematocyst is discharged Some threads merely trap prey or predators; others have spines that penetrate and inject paralyzing toxins
What can the nematocysts do to humans?
Two Main Body Plans outer epithelium (epidermis) Polyp mesoglea (matrix) Medusa inner epithelium (gastrodermis) Fig. 25-12, p.410
Polyp is vase-shaped Mouth is upward Sessile Produces the medusae Medusa is bell-shaped Mouth is downward Has more mesoglea Tentacles found around margin of bell Motile Produces eggs and sperm
Class Phylum
Class Anthozoa Sea Anemones Solitary polyps Upward turned oral disk contains mouth surrounded by hollow tentacles containing nematocysts
Class Anthozoa - Corals Resemble sea anemones encased in CaCO 3 Responsible for coral reefs by slow accumulation of limestone
Class Hydrozoa - Hydra Dominant polyp stage Portuguese Man of War is colony of polyps Original polyp becomes the gas-filled float
Nerve Net of Hydra
Class Scyphozoa True Jellies Helmet Jelly
Class Cubozoa Box Jellies
The Flatworms The Simplest Organ Systems
Phylum Platyhelminthes Bilateral Symmetry Moderate cephalization Triploblastic Possess several distinct organs, organ systems and true muscles Possess an incomplete digestive tract only one opening No coelom
Class Turbellaria Marine or freshwater and moist terrestrial habitats
Planarians Carnivorous eat small animals and carrion Breathe by diffusion through skin Flattened body places all cells close to water Flame cells excretory apparatus fxn to maintain water balance Ammonia wastes diffuse from cells to water Move by means of cilia on ventral surface to glide along film of mucus
Pharynx sucks up food and expels wastes
Reproduce asexually by transverse fission Mid-body constriction separates the parent into two halves, each of which regenerates the missing portion
Reproduces sexually by crossfertilization of hermaphroditic forms
Muscular contractions produce undulations which allow some to swim Eyespots on head detect light Pair of lateral auricles detect environment Rudimentary brain (ganglia) capable of simple learning
Class Trematoda PARASITIC feed on a host Cause weight loss BLOOD FLUKES and LIVER FLUKES Suckers present for attaching to host internal organs Majority are hermaphroditic
Life cycle of Schistosoma japonicum Infects 200 million people/year Human is the definitive (1 ) host where the mature parasite lives Snail is the intermediate (2 ) host where the immature stage lives
TAPEWORMS Class Cestoda Parasites of vertebrate digestive systems Scolex head armed with suckers and/or hooks that help maintain position by attaching to intestinal lining
Proglottids long ribbon of units located behind scolex Filled with reproductive organs No digestive system
Life Cycle Mature proglottids fill with eggs, are released from posterior end of worm, pass from body with feces Eggs are eaten by intermediate host and larva develops, usually in muscle tissue Definitive host becomes infected when it eats an intermediate host containing the larvae *Cook your beef and pork WELL DONE
Life cycle of the beef tapeworm Taenia saginata. Can grow to be 25 meters long.
The Annelids Segmented worms
Phylum Annelida True coelom well-developed and fluid-filled serves as hydrostatic skeleton, permits development of complex organ systems, protects internal structures, permits internal organs to fxn separately from the body wall muscles Segmented (repeated body parts) provides for specialization of diff body regions
Class Oligochaeta / Clitellata The earthworms - (scavengers) Feed on soil and detritus decaying org matter Aerate the soil important to farmers Few bristles (setae) per segment used for traction while crawling and burrowing
Complete digestive system divided into parts Each part specialized for a specific fxn in digestion Pharynx esophagus crop gizzard intestine *Excretory system found in each segment
Closed Circulatory System Hgb present in blood cells Dorsal and ventral longitudinal vessels connected by pairs of vessels 5 pairs of hearts circle the esophagus gas exchange thru skin
Nervous System Pair of cerebral ganglia (rudimentary brain) lie above pharynx
Reproduction hermaphroditic Worms X sperm and store it The clitellum secretes a mucous cocoon - slides along worm picking up its eggs and then the stored sperm Cocoon slips off worm into soil and protects embryos during development
Movement Muscles in each segment contract and elongate
Leeches Class Hirundinea Carnivorous predators &/or parasites
Blade-like jaws - slit the host s skin or secrete enzyme that digests a hole in the skin Secretes numbing chem to prevent detection of the incision Secrete hirudin protein that prevents blood clotting
Medicinal Use Used to treat bruised tissues and for stimulating circulation of blood to fingers and toes reattached after being severed
Colored SEM of teeth of medicinal leech UP CLOSE AND PERSONAL
Following failed venous reconstruction with vein grafts, leeches were applied and color improved dramatically. Application continued every 4 to 6 hours. 5 days postoperatively, active range of motion was begun. 8 days postoperatively, venous flow was sufficiently restored. 3 weeks postoperatively, a skin graft was performed. 6 weeks postoperatively, following treatment with active and passive movement as well as coban taping, the finger has a TAM of 224 degrees. Leeches U.S.A. LTD
A 45-year-old, white male patient who suffered a complete avulsion of the upper twothirds of his right ear. The ear was reattached. 24 hrs after surgery 48 hrs 72 hrs 6 days 2 months after surgery Leeches U.S.A. LTD
Phylum Nematoda The Roundworms
The Nematodes Cylindrical, bilateral bodies with tapered ends Caenorhabditis elegans species used by scientists for experiments Small, tiny, transparent, only 959 body cells Easy to observe and manipulate http://tuebingen.mpg.de/en/homepage/detail/the-reason-worms-dont-have-legs-and-arestill-able-to-accomplisch-everything.html
Many are agricultural pests Some are animal parasites: Ascaris lumbricoides largest intestinal worm to infect humans Cause stomach pain, vomiting, fever, wheezing, and abdominal tenderness and worm move through intestines
Trichinella spiralis Attach to intestines of pigs and game animals Eggs develop and migrate to blood and muscles Causes Trichinosis
Wuchereria bancrofti causes elephantiasis
Pinworms caused by Enterobius vermicularis live in the human rectum Common in young children
Phylum Mollusca
Phylum Mollusca Snails, slugs, oysters, clams, octopuses, squids Bilateral Symmetry Soft bodied, most protected by hard CaCO 3 shell Squids and octopuses have reduced, internalized shell or no shell
3 parts Molluscan Body Plan Foot for locomotion Visceral Mass containing most of the internal organs Mantle heavy fold of tissue that surrounds the visceral mass and secretes the shell Radula present in many molluscs fxns as a rasping tongue to scape food from surfaces
Class Bivalvia Clams, oysters, mussels, scallops Shell divided in 2 halves May extend foot for mobility or anchorage Mantle contains gills for gas X and feeding Most are suspension feeders Traps small food particles in mucus coating of gills and use cilia to move particles to mouth Water enters incurrent siphon, moves over gills, exits an excurrent siphon No radula or distinct head
Sedentary lives Use foot as anchor in sand/mud Sessile mussels secrete threads that anchor them to rocks, docks or other hard surfaces
Scallops propel themselves along the sea floor by flapping their shells Light sensitive eyes of scallop
Class Gastropoda Snails and Slugs Herbivores - use radula to scrape food Torsion during embryonic development Causes anus to develop above head of adult Most have shell (exceptions are slugs and nudibranchs) Many have distinct heads with eyes at tips of tentacles
Class Cephalopoda Squids and octopuses Carnivores Use beaklike jaws to crush prey Mouth is at center of several long tentacles Mantle covers visceral mass Shell reduced and internal in Squids Shell totally absent in Octopuses
Closed circulatory system blood is always contained in vessels Well developed nervous system complex brains capable of learning Well developed sense organs
Chambered Nautilus Only shelled cephalopod alive today
Squids Swim backward in open water
Octopuses Usually move along sea floor in search for food instead of swimming in open water
Phylum Echinodermata
1 ly bottom dwelling marine animals 5-pointed radial symmetry as adults Larvae are free-swimming, bilateral, filterfeeders Endoskeleton of calcium-rich ossicles
Class Asteroidea Sea stars 5 or more arms extending from a central disc Tube feet on undersurface of arms Regeneration abilities
Class Holothuroidea Sea Cucumbers
Class Echinoidea Sea urchins and sand dollars
Class Ophiuroidea Brittle stars No suckers on tube feet
Class Crinoidea Sea Lilies Mouths point upward Used in suspension feeding
Class Concentricycloidea Sea daisies
Phylum Arthropoda The most successful phylum
Arthropods Segmented bodies Jointed appendages modified for walking, feeding, sensory reception, copulation and defense. Covered by cuticle exoskeleton constructed of layers of chitin and protein
Exoskeleton thin and flexible in joints, thick and hard elsewhere Provides protection and points of attachment for muscles Impermeable to water Must be shed for animal to grow (molt) and new one is secreted
Cephalization
Gas X Feathery gills in aquatic species Tracheal system in insects Book-lungs in other terrestrial forms (spiders)