Porocytes

specialized pinacocytes that regulate water circulation; make pathways

Mesohyl

a jelly-like layer (mostly collagen) below pinacocytes in sponges. contains mesenchyme cells

Monoecious

"one house"; organism has both male and female gamete producing structures (sperm and egg in one)

Dioecious

separate sexes

Gemmules

internal capsules of amoeboid cells that resist freezing and drying

Cnidocytes

specialized cells used for defense, feeding, and attachment (can be epidermal or gastrodermal)

Nematocysts

contained in some cnidocytes; discharge tubes armed with spines and toxins

Statocysts

small sac surrounding a calcium carbonate statolith that detects tilting in an organism

Colloblasts

adhesive cells

Parenchyma

a spongy mass of undifferentiated mesoderm cells around viscera, muscles, or epithelial cells (in addition to epidermis and gastrodermis)

Parthenogenesis

a form of asexual reproduction where it is all female reproduction (no male fertilization needed)

Dimorphic

two different forms exist (body types)

Molting

the periodic shedding and replacement or the body covering (cuticle or exoskeleton)

Poisonous v. Venomous

- poisonous: toxins are ingested/absorbed/inhaled - venomous: toxins are injected

Monoecious v. Dioecious

Monoecious animals have both reproductive capabilities (sperm and egg); dioecious has separate sexes

Phylum Porifera- Characteristics

- aquatic (mostly marine) - asymmetrical - no true tissues or organs (loosely organized interdependent cells)

Phylum Porifera- Pinacocyte Cells

- thin, flat cells that line the outer surface of the sponge can be mildly contractile - porocytes: regulate water circulation

Phylum Porifera- Mesenchyme (amoeboid) Cells

specialized for reproduction, secreting skeletal elements, transporting/storing food, and forming contractile rings around openings in the sponge wall

Phylum Porifera- Choanocyte (collar) Cells

- lie below the mesohyl and line the inner chamber - flagellated; create water currents - the cell collar filters food particles from the water

Phylum Porifera- Spongocoels

inner chambers in sponges

Phylum Porifera- Ostia/Dermal Pores

outer openings of porocytes (water inflow)

Phylum Porifera- Osculum

opening (can be one or more) to spongocoel

Phylum Porifera- Canals

incurrent, radial, and excurrent canals in branched sponges

Phylum Porifera- Ascon Body Form

Phylum Porifera- Sycon

Phylum Porifera- Leucon

Phylum Porifera- Spicules

needle-like spikes, take a variety of shapes, made of calcium carbonate or silica; skeleton of sponges

Phylum Porifera- Spongin

fibrous protein made of collagen; skeleton of sponges

Phylum Porifera- Maintenance Functions

- filter feed on bacteria, algae, etc - choanocytes trap food; mesenchyme cells transport it - waste diffuses directly into water - no nervous system

Phylum Porifera- Sexual Reproduction

- most do not self fertilize - some choanocytes lose their flagella and undergo meiosis to form flagellated sperm or eggs - egg/sperm is released from oscula, and fertilization occurs in open water

Phylum Porifera- Asexual Reproduction

- budding, fragmentation, fission, etc - some species form gemmules

Phylum Cnidaria- Characteristics

- mostly marine - radial (or biradial) symmetry - gastrovascular cavity- blind cavity w/ single opening: a mouth - diploblastic

Phylum Cnidaria- Specialized Cells

- cnidocytes: aid in defense, feeding, or attachment; can contain nematocysts (tubes with spines/toxins)

Phylum Cnidaria- Polyp Body Form

Phylum Cnidaria- Medusa Body Form

Phylum Cnidaria- Alternation of Generations

- life history may involve alternation of generations (both polyp and medusa stages) - in some groups, one of the stages is absent or reduced

Phylum Cnidaria- Maintenance Functions

- gastrovascular cavity used for digestion, exchange of gases, metabolic wastes, and discharge of gametes (thru mouth) - feed on small crustaceans or fish - digestion partially extracellular and intracellular - gas/waste exchange thru simple diffusion - water filled gastrovascular cavity provides a hydrostatic skeleton

Phylum Cnidaria- Movement

- polyps move slowly by somersaulting, gliding, or walking on tentacles - medusae swim and float - water and surface winds responsible for most horizontal movement - vertical movements from pulses of contractile cells that drive water from the bell

Phylum Cnidaria- Nervous System

- two dimensional nerve net - some have statocysts for tilt detection

Phylum Cnidaria- Reproduction

- asexual: budding, regeneration (medusa form from polyp) - sexual: external; free-swimming ciliated planula larvae settle onto a substrate

Phylum Cnidaria- Class Hydrozoa

- nematocysts in epidermis - mesoglea is mostly acellular - obelia: a colony of hydrozoans - Ex: Hydra; Siphonophora (order)

Phylum Cnidaria- Class Scyphozoa

- "true jellyfish" - mesoglea contains ameboid cells - cnidocytes in gastrointestinal/epidermis - display negative photo-taxis (rise in the dark)

Phylum Cnidaria- Class Cuboza

- cube shaped medusa w/ stinging tentacles - some are dangerous to humans

Phylum Cnidaria- Class Staurozoa

- stalked like jellyfish - polyps w/ oral ends that look like medusa (no medusa stage) - have crawling, non-ciliated larvae

Phylum Cnidaria- Class Anthozoa

- sea anemones and corals - medusa stage absent - mouth leads to pharynx - mesenteries (membranes) bear cnidocytes and gonads and divide the gastrovascular cavity into sections - internal biradial symmetry - polyps attach via pedal disk

Phylum Cnidaria- Sea Anemones

- limited locomotion - feed on invertebrates and fish - some have symbiotic relations with cleaner fish or crustaceans - reproduce via pedal laceration or longitudinal fission

Phylum Cnidaria- Corals

- hard corals: calcium carbonate exoskeleton - soft corals: no calcium carbonate exoskeleton - zooxanthellae: algae that removes CO2 to promote coral reef building

Phylum Ctenophora- Characteristics

- gelatinous - swim using 8 comb rows - diploblastic (could be triploblastic) - biradial symmetry - branched gastrovascular canal system

Phylum Ctenophora- Feeding/Reproduction

- feed on plankton and small invertebrates - no tentacles and don't sting! - reproduction: monoecious with external fertilization

Phylogenic Considerations of Porifera, Cnidaria, and Ctenophora

- sponges are the most primitive animals - cnidarians arose early; primitive anthozoans may have been ancestors to other groups - ctenophores are similar to cnidarians, but direct relationship is unclear

Lophotrochozoans

protosomes that DO NOT molt

Ecdysozoans

protosomes that DO molt

Triploblastic, Acoelomate Body Plan

- Five Phyla - Acoelomorpha, Platyhelminthes, Nemertea, Gastrotricha, and Cycliophora - bilateral - acoelomate: no body cavity

Phylum Acoelomorpha

- small, flattened marine worms - recently split from Platyhelminthes - primitive digestion system - asexual reproduction

Phylum Platyhelminthes- Characteristics

- unsegmented or strobilated - distinct head/centralization of nervous system - blind-sac body - most monoecious

Phylum Platyhelminthes- Class Turbellaria

- free-living - have a ciliated epidermis that help with locomotion

Class Turbellaria- Digestion

- most carnivorous - incomplete digestive tract - tube-like pharynx

Class Turbellaria- Gas Exchange

no circulatory system or respiratory organs - gases exchanged through body wall (diffusion)

Class Turbellaria- Osmoregulation

- marine: near osmotic equilibrium - freshwater: hypertonic, must osmoregulate - protonephridia: tubules along parenchyma tissue (first kidney) - flame cells: tiny, hollow enlargements at the tips of branches tubules with beating cilia that create negative pressure

Class Turbellaria- Nervous System

- nerve net with longitudinal & lateral nerve cords - cerebral ganglia (primitive brain) - auricles: sensory lobes with chemoreceptors and ocelli (eyespots)

Class Turbellaria- Reproduction

- asexual: by transverse fission (divide into anterior & posterior animal) - monoecious with testes & ovaries the same animal - sexual: reciprocal sperm exchange between copulating animals - eggs are deposited in cocoons (some overwinter) - larvae usually resemble adults

Phylum Platyhelminthes- Class Monogenea

-ectoparasites of fish - opishaptor: posterior attachment organ - monoecious

Phylum Platyhelminthes- Class Trematoda

- parasitic - epidermis is a tegument - body flat and elongated

Class Trematoda- Digestive System

- oral sucker and acetabulum - anterior mouth - digestive system divides into two blind pouches called cecae

Class Trematoda- Life Cycle

Miracidium penetrates snail > transforms into sporocyst > rediae > cercariae > penetrate final host > metacercariae

Phylum Platyhelminthes- Class Cestoidea

- highly specialized endoparasites - lack mouth and digestive system - made up of long repeating units called proglottids

Class Cestoidea- Body Regions

- scolex: holdfast structure containing system of suckers and sometimes hooks (in a rostellum) - neck: immature proglottids - strobila: series of proglottids, which produce eggs when mature

Class Cestoidea- Structural Adaptations

- tegument: only means of absorbing nutrients - reduced nervous system: nerve mass in scolex and a pair of lateral nerve cords - simple protonephridial system

Class Cestoidea- Reproduction

- monoecious - fertilized eggs accumulate in gravid proglottids and other organs degenerate - gravid proglottids breaks off and passes in the feces of host - eggs consumed by intermediate host

Class Cestoidea- Common Tapeworms

beef, pork, fish tapeworms

Phylum Nemertea

- ribbon worms - extendable proboscis for feeding - up to 30m long - have a fluid-filled sac that acts like a primitive coelom - complete digestive tract and closed circulatory system - dioecious

Phylum Gastrotricha

- occur in sediment - complete digestive system - monoecious (marine) or parthenogenesis (freshwater) - no larval stage

Phylum Cycliophora

- most recently described phylum - live on mouthparts of lobsters (commensalism) - strange reproductive behavior (dioecious)

Pseudocoelomate Body Plan

seven phyla (2 lophotrochozoan and 5 ecdysozoan)

Pseudocolemates- Characteristics

- pseudocoelom (false body cavity); often fluid filled - serves in circulation, digestion, and locomotion (hydrostatic skeleton) - have protective non-cellular cuticle - complete digestive tract in most - protonephridia; but no respiratory or circulatory organs - no well formed head - fixed number of somatic cells at maturity

Phylum Rotifera- Characteristics

- cilia surrounding mouth that beat in cycle to create a wave to draw food in - gas exchange/waste diffusion across body wall - have a "foot" to attach to substrates - pharynx with mastax (jaws)

Phylum Rotifera- Facultative Parthenogenesis

- females can either produce fertilized or unfertilized eggs depending on environmental conditions - produce diploid by mitosis (amitic) or haploid by meiosis (mictic) - unfertilized: male - fertilized: female

Phylum Acanthocephala

- two hosts (arthropod and vertebrate) - retractable proboscis - no digestive system

Phylum Nematoda- General Characteristics

- Ubiquitous - parasitic or free-living (important in decomposition)

Phylum Nematoda- External Characteristics

-tapered at both ends - outer cuticle molted 4 times during maturation - have amphids and phasmids (chemoreceptors)

Phylum Nematoda- Internal Characteristics

- longitudinal muscles result in thrashing movement patterns - complete digestive system; some with lips, teeth, jaws, or other specialized feeding structures - anterior nerve ring with nerves extending from it

Phylum Nematoda- Osmoregulation

- 2 very unique systems - glandular system : free living nematodes have ventral gland cells called renettes, that absorb wastes from the pseudocoelom and empties them outside via a pore - tubular system : parasitic nematodes; renettes unite to form a large, long canal with an excretory pore

Phylum Nematoda- Reproduction

-usually dioecious, dimorphic (2 body types, males smaller than females) - female reproductive structures paired; male has single testis - fertilization internal via copulation - some lay eggs (oviparous); others give birth to larvae (ovoviviparous) - larvae resemble small adults

Phylum Nematoda- Human Parasites

- typical parasite adaptations (high reproductive capability, ability to find host, resistance to host's enzymes) - life cycle is not as complicated as flukes or tapeworms - usually only a single host - some are annoying (e.g., pinworms); others cause severe problems (filarial worms)

Phylum Annelida- Characteristics

- segmented worms - display metamerism - complete digestive system - respiratory gases diffuse across body wall - closed circulatory system w/ contractile tissue - paired ganglia in head region -excrete ammonia (aquatic) or urea (terrestrial) - chloragogen tissue (primitive liver)

Phylum Annelida- Metamerism

- divison of body into serially repeated sections along anterior/posterior axis - each section has paired excretory, nervous, and circulatory structures

Advantages of Metamerism

- hydrostatic compartments - lessens impact of injury - specialization/complexity

Phylum Annelida- Class Polychaeta

tubeworms, clamworms, and fanworms

Class Polychaeta- Locomotion

• parapodia with setae (bristles): lateral extensions used for locomotion, also assist in gas exchange (increased surface area) move by walking with parapodia, crawling with undulations, or swimming some are sedentary and live in tubes

Class Polychaeta- Body Form

greatest cephalization - prostomium (lobe dorsal and anterior to the mouth that has sensory organs like eyes or antennae)

Class Polychaeta- Feeding

some have proboscis, some herbivores, scavengers, or detrivores, fan worms filter feed

Class Polychaeta- Reproduction/Regeneration

- can regenerate lost segments; some have natural break points - asexual: budding or fission - sexual: dioecious w/ external fertilization and trochophore larvae

Class Polychaeta- Epitoky

- the formation of reproductive individual different form non-reproductive individual - atoke: non reproductive - epitoke: reproductive

Phylum Annelida- Class Clitella

- earthworms, leeches - clitellum used in cocoon formation - monoecious

Class Clitella- Subclass Oligochaeta

- earthworms - burrowing - lack parapodia - few setae, and low degree of cephalization

Subclass Oligochaeta- Locomotion

- move with antagonistic contraction of circular and longitudinal muscles - small setae help anchor the worm - bulging and elongating body segments in waves cause the worm to move forward

Subclass Oligochaeta- Feeding

- small conical prostomium acts like a wedge while burrowing - feed on detritus and vegetation - soil is swallowed (important for decomposition)

Subclass Oligochaeta- Reproduction

- monoecious, reproduce sexually via reciprocal fertilization (exchange sperm) - cocoon of mucous and chitinous materials produced by clitellum - eggs, sperm, and food (albumen) deposited in cocoon where fertilization takes place - young earthworms hatch from cocoon (no larvae)

Class Clitella- Subclass Hirudinea

- leeches - lack parapodia, setae absent in most - little cephalization; anterior and posterior suckers - move in looping motion or swim by undulations

Subclass Hirudinea- Feeding

prey on small invertebrates or feed on blood of vertebrates (ectoparasitic)