Exam 3 - Invert Zoology

Chapters 13 -

Lophotrochozoa

shells

spicules

calcareous

chaetae

Phylum Mollusca

Synapomorphies

• reduced coelom

• open circulatory system - hemoceal

• mantle - epidermal layer

• calcareous sclerites/shell

• muscular foot - locomotion

• radula - specialized feeding structure

• heart - single ventricle

• ctenidia - function as “gills”

Mantle

Epidermal layer in mollusca

Radula

Specialized feeding structure in mollusca

Ctenidia

Function as “gills” for mollusca

Phylum Mollusca - Class Caudofoveata

Aplacophorans - imbricating scales

• loss of foot

Phylum Mollusca - Class Solenogastres

Aplacophorans - copulatory spicules

• loss of ctenidia

Phylum Mollusca - Class Gastropoda

Snails, slugs, limpets - torsion, operculum

Only mollusks found in terrestrial environments

Torsion

Twisting body mass 180 degrees in mollusca

Operculum

Trap-door, hard lid-like structure in mollusca

Phylum Mollusca - Class Bivalvia

Clams - 2 shell halves, loss of radula

Phylum Mollusca - Class Scaphopoda

Tusk shells - loss of heart and ctenidia

Phylum Mollusca - Class Cephalopoda

Nautilus, Squid, Octopus - closed circulatory system, modified foot

Chambered shell to fill with gases to help float - Nautilus

Phylum Mollusca - Body Plan

Microscopic to 13 meters long

Three regions:

• Head

• Foot

• Visceral mass (surrounded by mantle)

Body Wall

• cuticle

• epidermis

• muscles - three layers

Shell (black)

• aragonite or calcite

• outer prismatic layer - shiny

• inner laminar layer (Nacre)

Phylum Mollusca - Class Gastropoda Body Plan

Spiraled shell

Shell loss

Torsion

Spire

Spire

Last whirl of the shell in gastropods

Phylum Mollusca - Class Caudofaveata Locomotion

• Infaunal burrowers

• Peristaltic movements

Phylum Mollusca - Class Solengastres Locomotion

symbiotic or cnidarians

Phylum Mollusca - Class Gastropoda Locomotion

• creeping sole

• swimming

• distinct foot

• contraction waves

Phylum Mollusca - Class Bivalvia Locomotion

distinct foot

infaunal burrowers

epifaunal

swimming

Phylum Mollusca - Class Cephalopoda Locomotion

Modified foot

Crawling

Swimming (jet propulsion)

• contract muscles, pull water into mantle activity

• relax muscles, expels water through siphon

Phylum Mollusca - Feeding

Radula - can extend

• browsing and scraping

• herbivory

• carnivorous grazing

• predation

Phylum Mollusca - Class Gastropoda Feeding

Primarily eating microalgae

Carnivorous

• borers

• buccal mass

• venom injecting teeth on proboscis

• parasitism

• kleptocnidae

• symbiosis

Phylum Mollusca - Class Polyplacophora Feeding

Herbivorous grazers

Small invertebrates

Phylum Mollusca - Class Monoplacophora

Limpet-like - deep sea

Phylum Mollusca - Class Polyplacophora

Chitons - 8 shell valves

Phylum Mollusca - Class Monoplacophora Feeding

Deposit - feeders

Phylum Mollusca - Class Scaphopoda Feeding

Sticky terminal bulb and tentacles

Phylum Mollusca - Class Cephalopoda Feeding

Predatory carnivores

Neurotoxin

Phylum Mollusca - Class Bivalvia Feeding

No radula

Suspension feeding

• ctenidia - gills to filter

• siphons

Deposit feeding

Sessile predators

Symbiosis

Phylum Mollusca - Digestion

Complete gut

• extra cellular digestion in stomach (most common)

or

• intracellular digestion in digestive gland

Phylum Mollusca - Circulation/Gas exchange

Open circulatory system (hemocoel)

• hemocyanin - copper

• secondarily closed in cephalopods

Gas exchange

• ctenidia or gills

• body surface

• pneumostome (lung) - only in terrestrial mollusks

Phylum Mollusca - Excretion/Osmoregulation

Paired tubular nephridia

• aquatic turns waste into ammonia

• marine - osmoconformers

• freshwater to waste into hypoosmotic urine

Terrestrial turns waste into uric acid

Phylum Mollusca - Nervous System

Anterior ganglia

Paired ventral nerve cords

• pedal

• visceral

Cephalopoda - extreme cephalization

Phylum Mollusca - Sense Organs

Chemoreceptors

• osphradia - on the gills

• rhinophores - only in nudibranchs

Photoreceptors

• eyes

• mantle eyes

Olfactory organs

Statocysts - helps with knowing what is up and down

Tactile receptors

Phylum Mollusca - Cephalopoda

Countershading - helps camoflauge

Chromatophores - pigment containing cells controlled with muscle contractions

Bioluminescent

Ink - melanin and mucous, for defense and predation

Phylum Mollusca - Reproduction

Gonochoristic - separate sexes

Hermaphroditic - both male and female reproductive organs

Precopulatory behaviors - trying to “show off”

• terrestrial gastropods

• cephalopods

Phylum Mollusca - Development

Indirect

• trocophore larva

• veliger larva (gasropoda/bivalvia) - distinct larval stages

• glochidium larva (FW parasitic)

Mixed

• brood trochophore

• release veliger

Direct

• brood between gills

• cephalopods - lecithotrophic

Phylum Nemertea

Ribbon Worms

• few mm - several meters long

• benthic marine organisms

• coelomate (functionally acoelomate)

• eversible proboscis

Phylum Nemertea - Body Plan

Body wall

• epidermis: tacticle sensory cells, mucous gland cells, replacement cells

• dermis

• circular and longitidinal muscles

• mesenchyme

Phylum Nemertea - Support and Locomotion

Muscles

Hydrostatic mesenchyme

Cilia - small worms

Peristaltic waves - bigger worms

Undulatory swimming

Phylum Nemertea - Feeding and Digestion

Active predators

• proboscis

Scavengers

Ectoparasites

Complete gut

Phylum Nemertea - Circulation and Gas Exchange

Closed Circulatory System

• hemoglobin

Diffusion

Phylum Nemertea - Excretion and Osmoregulation

Protonephridia for both

Phylum Nemertea - Nervous System and Sense Organs

Cerebral ganglion

Pair of longitudinal nerve cords

Tactile

Eyes

Chemosensory - very advanced

Statocysts

Photoreceptors - eye like structures to perceive light

Phylum Nemertea - Reproduction and Development

Regeneration/Fragmentation

Sexual

External fertilization

Direct development - most common

Indirect development

• pilidium larva

Phylum Nemertea - Importance

Food web balance

Venom

Regeneration

Phylum Annelida

Segmented

Serial homology - metamerism, repeated structures in the body

0.5 mm to 3 m long

marine, brackish, freshwater, terrestrial

Phylum Annelida - Synapomorphies

Metamerism - serial homology

Chaetae - made of chitin

Phylum Annelida - Four Regions

Four regions

• prostomium - head

• peristomium - region around the mouth

• segments - body

• pygidium - posterior end

Cirri

Phylum Annelida - Segmented Trunk

Chaetae

Parapodia

• notopodium

• neuropodium

Phylum Annelida - Body Structure

Cuticle - outer layer

Epidermis

Peritoneum - lining the coelom

Muscles

Phylum Annelida - Support and Locomotion

Hydrostatic skeleton

Crawling/Swimming

• Polyonidae - scaleworms

Burrowing

Tube-dwellers

• Bioturbation - introducing air into the sediment

Phylum Annelida - Raptorial Feeding

Hunting predators

• small invertebrates

• dead organic material

• other worms

Ambush predators

Phylum Annelida - Deposit Feeding

Unselective

Selective

Phylum Annelida - Suspension Feeding

Tube dwellers

Permanent burrows

Radioles - structure that captures food particles

Phylum Annelida - Symbioses

Parasitism

Phylum Annelida - Digestion

Complete gut

Foregut

• poison, esophageal, and mucus glands

• Earthworms: crop and calciferous glands

Midgut

• endodermally derived

• secretory cells

Hindgut

• excretion

Phylum Annelida - Circulation/Gas exchange

Closed circulatory system

• blood movement via muscles

• pumping organs

• hemoglobin

Phylum Annelida - Excretion/Osmoregulation

Metanephridia

• nephrostomes

• ammonia

Osmoregulation

• marine - osmoconformers

• estuarine - osmoregulators

• terrestrial - osmoregulators/conformers

• freshwater - osmoregulators

Phylum Annelida - Nervous System

Central nervous system

• Dorsal Cerebral Ganglion: forebrain, midbrain, hindbrain

• Paired circumcenteric connectives

• Ventral longitudinal nerve cord(s)

Phylum Annelida - Sense Organs

Tactile receptors

Photoreceptors

Chemoreceptors

• nuchal organs - pit with cilia inside

Statocysts

Phylum Annelida - Asexual Reproduction

Regeneration

• Neuroendocrine secretions

Epitoky - clonal reproduction

Phylum Annelida - Sexual Reproduction

Gonochoristic

• External fertilization - indirect development

• Internal fertilization - mixed or direct development

• Epitoky - epitokes release gametes into environment

Hermaphroditic

• clitellates - clitellum

Phylum Annelida - Development

Trochophore larva

Direct development - little metamorphosis

Clitellates - cocoon

Phylum Annelida - Importance

Bioturbation - introducing oxygen into the sediment

Important food source

Predators

Lophophorates

Lophophore

Prosome, Mesosome, Metasome

Sessile

U-shaped gut

Marine (few freshwater)

Phylum Phoronida - Body Plan

Cylindrical tube

Intertidal - 400m

1-25 cm

Trimeric coelomates

Hydrostatic qualities

Phylum Phoronida - Feeding/Digestion

Hollow tentacles

Ciliary-mucus suspension feeders

U-shaped gut

Intracellular digestion

Phylum Phoronida - Circulation and Excretion

Extensive closed circulatory system

• close association with stomach

Gas exchange in tentacles

Two metanephridia

• nephrostomes

• gametes

Phylum Phoronida - Nervous System

Lacks cerebral ganglion

Sensory neurons

Phylum Phoronida - Reproduction

Regeneration

Asexual

• transverse fission

• budding

Sexual

• gonochoristic/hermaphroditic

• internal fertilization

• broadcast spawning

Phylum Bryozoa - Body plan

Colonies

Cystid

Polypide

• autozooid

• heterozooid

Hydrostatic skeleton

• fluid-filled coelom

• muscles

Zooid interconnections

• pores

• funiculus

Phylum Bryozoa - Feeding/Digestion

Lophophore

Suspension feeders

Intra and extracellular digestion

Phylum Bryozoa - Circulation/Excretion

No structural circulatory system

• diffusion

• coelom, pores, funiculus

Gas exchange polypide

Brown bodies

Phylum Bryozoa - Nervous System

Cerebral ganglion and circumoral nerve ring

Tactile receptors

• tentacles

• avicularia

Larvae

• apical organ

• pyriform organ

Geotaxis

Phototaxis

Phylum Bryozoa - Asexual Reproduction

Regeneration

Budding

Statoblasts

Phylum Bryozoa - Development

Indirect development

Radial holoblastic cleavage

Free-swimming larvae

• lecithotrophic or planktotrophic

• ancestrula

Phylum Brachiopoda - Body Plan

Dorsoventrally oriented valves

All depths

204 cm

Pedicle - foot

Shells, hard structures

Mantle

Phylum Brachiopoda - Feeding and Digestion

Lophophore

• tentacle bearing arms

• always protected

Suspension feeders, ciliary current

Intracellular digestion

Phylum Brachiopoda - Circulation/Excretion

Open circulatory system

• contractile heart

• canals (no vessels)

Gas exchange in tentacles and mantle

Two metanephridia

• nephrostomes

• gametes

Phylum Brachiopoda - Nervous System

Dorsal and ventral cerebral ganglia

• circumcentric nerve ring

Sensory organs

• tactile receptors

• chemoreceptors

• statocysts

• eyes in larvae

Phylum Brachiopoda - Reproduction and Development

Sexual

• gonochoristic

• external fertilization

• broadcast spawning

Holoblastic radial cleavage

Indirect or mixed development

Lecithotrophic

Lophophorates - Importance

Food

Bioindicators

Evodevo

Reef stabilization

Habitat

Sedimentary rock dating

Link pelagic primary production to benthic ecosystem

Phylum Phoronida - Development

Sprial cleavage

Actinotroch larvae

Phylum Bryozoa - Sexual Reproduction

Hermaphroditic

Internal fertilization

Spawning or brooding of embryos

Rhoupazoa

Duo-gland organs

Acoelomate

No anus

Phylum Platyhelminthes

Unsegmented

Triploblastic

Acoelomate

Bilateral symmetry

Incomplete gut

Cephalization

Free-living

Parasitic

• trematodes (flukes)

• monogeneans (flukes)

• cestodeans (tapeworms)

Internal plumbing

Unilateral movement

Higher energy demands

Neoblasts

Phylum Platyhelminthes - Body Plan

Free-living

• dorsoventrally flattened

• head with ventral mouth

Parasitic

• flukes (oval/leaf shaped with hooks/suckers)

• tapeworms (ribbon like) - scolex, neck, proglottids

Phylum Platyhelminthes - Body wall

Free living

• epidermis with gland cells and nerve endings

• rhabdoids

Flukes and Tapeworms

• tegument

• microtriches

Phylum Platyhelminthes - Support/Locomotion

Hydrostatic mesenchyme

Free living

• cilia powered gliding

Flukes

• adhesive organs (hooks)

Tapeworms

• scolex

Phylum Platyhelminthes - Free-living Feeding & Digestion

• carnivorous predators or scavengers

• chemoreception

• Incomplete gut - mouth, pharynx, intestine, initial digestion extracellular

Phylum Platyhelminthes - Flukes and Tapeworms Feeding & Digestion

Eat host tissue

Flukes

• mouths

Tapeworms

• across tegument

• alter host behavior

Phylum Platyhelminthes - Circulation/Osmoregulation

No circulatory system

Excretion

• protonephridia

Phylum Platyhelminthes - Free-living Nervous System

Net like

Ladder like

CNS

Receptor types

• tactile

• chemo

• statocysts

• photo - negatively phototactic

Phylum Platyhelminthes - Flukes and Tapeworms Nervous System

Ladder-like

Tactile receptors

Phylum Platyhelminthes - Asexual reproduction

Free living

• transverse fission

• regeneration

Flukes

• intermediate hosts

Phylum Platyhelminthes - Free-living sexual reproduction

Hermaphroditic - separate gonopores

Zygotes retained by parent or laid in egg masses

• oviparous/ovoviviparous

• direct development

• spiral cleavage

Phylum Platyhelminthes - Fluke Sexual Reproduction

Hermaphroditic

High fecundity

Single host

Holoblastic cleavage

Phylum Platyhelminthes - Tapeworm Sexual Reproduction

Hermaphroditic

High fecundity

One or more intermediate host