Exam 2 - Invert Zoology

Chapters 6 - 12

Monomorphic

One body form, not sessile

Hermaphrodites

Self fertilizing

Cypdipped Larval Stage

Free swimming developmental stage that looks like adult form

Phylum Ctenophora

• diploblastic

• biradial symmetric

Ctenophora Tissues

True tissues

• epidermis

• gastrodermis

• mesenchyme

Ctenophora Body Plan

Retractile tentacles

Colloblasts - sticky cells on the tentacles

Ctenes - comb rows covered in silia

Apical sense organ - sense gravity

Ctenophora Support and Movement

Elastic mesenchyme - Outer membrane of ctenophora

Cilia - movement

Ctenophora Feeding and Digestion

Predators

• colloblasts

• kleptocnidae

Gastrovascular canal system

• anal pores

• circulation

Ctenophora Nervous System

Nerve net

• subepidermal plexus - continuous string of neurons for direct communication

Apical sense organ (Statolith)

Ctenophora Reproduction

Asexual

• regeneration

Sexual

• most hermaphroditic

• cydippid larvae

• planktrophic - drift in currents

• cell fate determinate

Cnidaria

Snyapomorphies

• Diploblastic

• Cnidae

• Polyp

• Planula larvae - only found in cnidarians

Cnidaria Three Major Lineages

Anthozoa

Endocnidozoa

Medusozoa

Subphylum Anthozoa

Subclass Hexacorallia

• 6 or fewer planes of symmetry

• simple tentacles

Subclass Octocorallia

• 8 planes of symmetry

Subclass Ceriantharia

• somewhat parasitic

Subphylum Endocnidozoa

Subclass Myxozoa

Subclass Polypodiozoa

Subphylum Medusozoa

Class Staurozoa

Class Cubozoa

• jellyfish like organisms

Class Scyphozoa

• true jellyfish

Class Hydrozoa

• jellyfish like organisms

Cnidaria Body Plan

Two true tissue layers

• ectoderm - epidermis

• endoderm - gastrodermis

Radial symmetry

Myoepithelial cells - primitive muscle cells

Polypoid form (polyp)

Subphyla Anthozoa and Medusozoa

Tubular structure

Outer epidermis, inner gastrodermis

Inner gut sac (coelenteron)

Thin mesogleal layer

Hypostome

Polypoid mouth

Polypoid form - Anthozoa

Hydrozoan Colonies

• gastrozooid - used for feeding

• dactlyozooid - defense

• gonozooid - reproduction

Polypoid form - Medusozoa

Hydrozoan Colonies

• Siphonophores

• Pneumatophore - gas filled float

• Nectophore - swimming bell

Medusoid Form

Subphylum Medusozoa

• bell or umbrella shaped

• thick mesogleal layer

• sexually reproducing stage

• manubrium - where mouth is attatched

• Coelenteron in umbrella

• Radial canals (gastrovascular system)

• Velum - tissue layer around the bell

Phylum Cnidaria - Support

Polypoid

• hydrostatic skeleton

• fibers, sediment

Medusoid

• middle layer- thin and flexible to cartilage like

Hard skeletal structures

• horny, wood like axial skeleton structures

• calcareous sclerites

• massive calcareous frameworks - anthozoans, hydrozoans

Phylum Cnidaria - Movement

Contractile elements derived from myoepithelial cells (not true muscles)

• circular fibers - tentacles

• longitudinal fibers - contract column

Polypoid

• creeping

• somersaults

• “swimming”

• burrowing

Mudosoid

• jet propulsion

• rowing

Phylum Cnidaria - Cnidae

Nematocysts - double walled capsules full of toxins with barbs used for catching prey

• anthozoa and medusozoa

Spriocysts - sticky cells

• hexacorallia only (anthozoa)

Ptychocysts - sticky cells

• cerianthids only (anthozoa)

Polar capsules

• class myxozoa - homologous

Cnidaria - Feeding & Digestion

Carnivores

• swimming prey

• tentacles or mouth

• digestion starts extracellularly and finishes intracellular

• incomplete gut

Phylum Cnidaria - Defense

Defense or sweeper tentacles

Secondary metabolites

Palytoxin - numbing toxin

Phylum Cnidaria - Interactions

Parasitism

• myxozoa - reduced structures, fish hosts

Mutualism - ex. clownfish living in anemones

Co-evolution

Phylum Cnidaria - Nervous System

Nerve Net

Phylum Cnidaria - Sensory System

Photoreceptors

Statocysts - balance

Luminescence

• aequorin - protein used to emit light with calcium is present

Phylum Cnidaria - Reproduction

Alternation of generations

Regeneration

Most gonochoristic

Scleractinians hermaphroditic (anthozoa: hexacorallia)

Cnidaria Strobilation

type of asexual reproduction

• Shedding layers to grow into new individuals

Phylum Cnidaria - Asexual reproduction

Subphylum anthozoa

• longitudinal fission

• pedal laceration

• tentacular shedding

• pathogensis

Subphylum medusozoa

• budding

• creeping frustrules

• fission

Subphylum Cnidaria - Sexual reproduction

Subphylum anthozoa

• spawning

• internal fertilization

• planktotrophic

Subphylum medusozoa

• copulation

• spawning

• fertilization on medusa

• lecithotrophic

Bilateria

• bilateral symmetry

• cephalization

• triploblastic

• mesodermally derived organs

Phylum Xenacoelomorpha

• dorsoventrally flattened

• marine

• incomplete digestive system

• direct development

• lacking excretory system

• cilia lined bodies - structurally different from other cilia

Phylum Xenacoelomorpha - Class Acoela

Subphylum Acoelomorpha

• Statocysts - georeceptor

• Rhabdoids - glands that produce mucous

• Sagittocysts - eject to capture prey/defense or reproduce

Phylum Xenacoelomorpha - Class Nemertodermatida

Subphylum Acoelomorpha

• Statoliths

• Eversible proboscis

Phylum Xenacoelomorpha - Subphylum Xenoturbellida

• Furrows

• Robust longitudinal muscles

Phylum Xenacoelomorpha - Support/Movement

• mesodermally derived structures

• cilia

Phylum Xenacoelomorpha - Nutrition/Gas exchange

• algae, crustaceans, worms, molluscs

• different feeding organs - pharynx simple, proboscis, broom organ, foregut

• Excretion/Gas exchange - through tissues, no specific structures

Phylum Xenacoelomorpha - Nervous System

• concentration of neurons forming a “brain”

• complex nerve net

• dorsal, lateral and ventral nerve cords

• all have Statocyst/Statoliths

Phylum Xenacoelomorpha - Reproduction

• Regeneration

• Asexual only in acoelem - transverse fission, longitudinal fission, budding

• Sexual - Hermaphrodites, Internal fertilization

Phylum Xenacoelomorpha - Development

• Direct development

• Cleavage - holoblastic radial, spiral duet cleavage

Phylum Xenacoelomorpha - Importance

Marine biomass

Nutrient cycling

Nephrozoa

Complex organs

Complete gut with anus

Kidney-bearing

Legacy names - Deuterostomia, Protostomia

Phylum Dicyemida

Simple solid body

• assymetrical

• robust longitudinal muscles

Obligate symbionts of cephalopods

Phylum Dicyemida - Reproduction

Asexual

• Vermiform embryos

Sexual

• Infusoriform embryos - fertilized eggs

Phylum Dicyemida - Development

• no germ layer

• pass out host with urine

Phylum Dicyemida - Importance

Evolution of parasitism

Cephalopod indicators

Gnathifera

Pharyngeal hard parts (jaws)

Phylum Gnathostomulida

marine, interstitial

prey, microbial regulators

Phylum Genathostomulida - Movement

cilia and mucous glands

Phylum Genathostomulida - Nutrition

Ingest bacteria and fungi

incomplete gut

complex jaw apparatus

Phylum Genathostomulida - Circulation/Gas exchange

diffusion

protonephridia - osmoregulation and removal of metabolic waste

Phylum Gnathostomulida - Nervous System

Brain, buccal ganglion, longitudinal nerve cords

sensory ciliary pits

Phylum Gnathostomulida - Reproduction

hermaphroditic

internal fertilization

deposit zygotes into habitat

Phylum Gnathostomulida - Development

Spiral cleavage

direct development

Phylum Rotifera - free-living

freshwater, marine

prey, nutrient cycling

water quality

Phylum Rotifera - Movement

foot with toes

retrocerebral organ - complex glandular system located near the brain

Phylum Rotifera - Nutrition

ingest bacteria and algae

complete gut

corona, mastax, trophi

Phylum Rotifera - Circulation/Gas exchange

Protonephridia

Phylum Rotifera - Nervous System

cerebral ganglion, longitudinal nerve cords

Phylum Rotifera - Reproduction

parthenogenesis

gonochoristic - strictly male or strictly female

deposit zygotes into habitat

Phylum Rotifera - Development

spiral cleavage

direct development (errant)

dispersal larvae (sessile)

Phylum Rotifera - parasitic Acanthocephalans

obligate intestinal parasites of vertebrates

• hook bearing proboscis

Parasitic Acanthocephalans - Nutrition

gut absent, absorb through body wall

Parasitic Acanthocephalans - Circulation/Gas exchange

diffusion

lacunar system

protonephridia absent

Parasitic Acanthocephalans - Nervous system

greatly reduced

Parasitic Acanthocephalans - Reproduction

gonochoristic

internal fertilization

Parasitic Acanthocephalans - Development

modified spiral cleavage

acanthor larva - spiny headed

Phylum Micrognathozoa

acoelomate

freshwater

head with prominent “jaw”

Phylum Micrognathozoa - Body structure/movement

epidermal plates

ciliophores

Phylum Micrognathozoa - Nutrition

Complex sclerotized jaw

incomplete gut

bacteria on moss/sand

Phylum Micrognathozoa - Circulation/Gas exchange

diffusion

paired nephridia

Phylum Micrognathozoa - Nervous system

brain, longitudinal nerve cords

collar receptors

apical ciliary tufts

phaosomes - optic organelles in photoreceptor cells

Phylum Micrognathozoa - Reproduction

parthenogenic

Phylum Micrognathozoa - Development

Summer egg

Winter egg

Phylum Chaetognatha

marine, planktonic, epibentic

consume copepods/zooplankton

grasping spines

multilayered epidermis

horizontal fins

closed seminal vesicles

Phylum Chaetognatha - Support/Movement

longitudinal muscle

true coelom/hydrostatic

hop-sink swimming

Phylum Chaetognatha - Nutrition

ambush predators

complete gut

some have toxins

Phylum Chaetognatha - Circulation/Gas exchange

diffusion

simple hemal system

Phylum Chaetognatha - Nervous system

loop: dorsal cerebral ganglion, eyes, corona cilata, esophageal ganglia, gut

ventral ganglion

ciliary receptors

Phylum Chaetognatha - Reproduction

hermaphroditic

internal fertilization

zygotes released into the environment

Phylum Chaetognatha - Development

holoblastic, spiral cleavage

direct development

48 hours!

Phylum Entoprocta

marine

cup-shaped calyx on stalk

U-shaped gut

food for flatworms and molluscs

Phylum Entoprocta - Body Structure/Movement

thin cuticle

longitudinal/oblique muscles

nodding - flicking of stalk

Phylum Entoprocta - Nutrition

ciliary suspension feeders

U-shaped gut

digestion in stomach/intestine

Phylum Entoprocta - Circulation/Gas exchange

complete gut

protonephridia - astrocytes

star-cell organ

diffusion

Phylum Entoprocta - Nervous system

subenteric ganglion

tactile receptors

Phylum Entoprocta - Reproduction

asexual budding

sexual sperm released into water

hermaphroditic, protandric

Phylum Entoprocta - Development

holoblastic, spiral cleavage

larvae feed in plankton

Phylum Cycliophora

lobster symbionts

suspension-feeding

acoelomate

protonephridia

U-shaped gut

diffusion

Phylum Cycliophora - Life Cycle

alternating sexual and asexual

larvae

• chordoid (feeding)

• promehtus (free-swimming)

• pandora (free-swimming)

dwarf males