BIOL 1030 Ch. 33 Lophotrochozoans

Bilateria

Triploblastic animals with bilateral symmetry

What are the clades that are included in Bilateria?

Basal clade: Acoela
Deuterostomia, Protostomia: Lophotrochozoa, Ecdysozoa, and Chaetognatha

Phylum Chaetognatha

Arrow worms
~70 living species

What are some characteristics of Phylum Chaetognatha?

- Centimeter sized range
- Arrow shaped, transparent body with a head, trunk, tail, and fins
- Has eyes
- Has powerful jaws with teeth
- Marine predators

What is the sister clade to Phylum Chaetognatha?

Protostomia

Lophotrochozoa

A non-molting triploblastic and bilateral diverse group composed of 18 phyla

What does the Lophotrochozoa name come from?

Lophophore and Trochophore

Lophophore

A horseshoe-shaped crown-like feeding structure with ciliated tentacles

Trochophore

A pear-shaped larva with a ring of cilia around its middle

What are the 18 phyla of Lophotrochozoa?

Ectoprocts, Brachiopoda, Phoronida, Gastrotricha, Cycliophora, Nemertea, Annelida, Siponucla, Echiura, Mollusca, Platyhelminthes, and Rotifera

Phylum Platyhelminthes

Flatworms
~ 20,000 species

What are some characteristics of Phylum Platyhelminthes?

- Living in all habitats
- Mostly parasitic
- Dorsoventrally flattened acoelomates
- Bilateral nervous system
- No respiratory or circulatory systems
- Has a digestive and excretory systems
- Hermaphrodites

Digestive system of Platyhelminthes

Incomplete with one opening

Excretory system of Platyhelminthes

Small tubules lined with ciliated flame bulbs (protonephridia)

Protonephridia

More primitive tubules with bundles of flame cells to remove waste materials out of body in flatworms, ribbon worms, and rotifers

Hermaphrodite

An organism with both male and female reproductive structures

What are the two lineages (subphyla) of a Platyhelminthes?

Catenulida and Rhabditophora

Subphyla Catenulida

Chain worms

What are some characteristics of Catenulida?

- Lives in freshwater
- Reproduces asexually by budding into chains of individuals

Subphyla Rhabditophora

Planarians, trematodes, and tapeworms

What are some characteristics of Rhabditophora?

- More diverse
- Found in marine and freshwater habitats
- Free-living and parasitic species

Class Turbellaria

Planarians

What are some characteristics of Class Turbellaria?

- Free-living rhabditophorans: Planarians
- Found in marine or freshwater
- Use ciliated epithelial cells for movement
- Have eyespots
- Use the pharynx for feeding

Class Trematoda

Flukes

What are some characteristics of Class Trematoda?

- Parasitic rhabditophorans: Trematodes
- All parasitic
- Resistant to digestive enzymes and host immune response
- Cause blood flukes

Class Cestoda

Tapeworms

What are some characteristics of Class Cestoda?

- All parasitic
- Resistant to digestive enzymes and host immune response
- No mouth or digestive tract
- Has a scolex and proglottids

Scolex

Attachment with suckers and hooks found in tapeworms

Proglottids

Units that contain sex organs and form a ribbon behind the scolex

Phylum Syndermata

Rotifers and Acanthocephalans

Rotifera

Wheel animals
~ 1800 species

What are some characteristics of Rotifera?

- Found in freshwater, marine, and damp soil
- Fluid-filled pseudocoelom
- Has an alimentary canal
- Reproduces through parthenogenesis
- Has a corona and hydrostatic skeleton

Alimentary canal

A digestive tube with a mouth and anus

Parthenogenesis

The reproductive process in which females produce female offspring from unfertilized eggs

Corona

A ciliated food-gathering organ at the tip of the head in filter feeders

Hydrostatic skeleton

A fluid skeleton in the pseudocoelom

Acanthocephalans

Thorny-headed worms

What are some characteristics of Acanthocephalans?

- Parasites of vertebrates
- No digestive tract

Phylum Ectoprocta

Moss animals
aka Bryozoans
~ 4500 species

What are some characteristics of Phylum Ectoprocta?

- Found in marine
- Small animals form colonies
- Coelomate
- Lophophore
- Has a zooecium
- Has a U-shaped alimentary canal

Zooecium

Calcareous or organic (chitin, protein) exoskeleton of Ectoprocta

Phylum Brachiopoda

Lamp shell
~ 355 species

What are some characteristics of Phylum Brachiopoda?

- All are marine
- Resembles clams but the two shells have different size
- Lophophore
- Has a pedicle and anchors to seafloor

Pedicle

A supporting column or stalk

Phylum Phoronida

Horseshoe worms

What are some characteristics of Phylum Phoronida?

- Marine
- Lophophore
- Worm-like animals in tubes
- U-shaped gut

Phylum Nemertea

Ribbon worms
~ 900 species

What are some characteristics of Phylum Nemertea?

- Marine
- Very long
- Has a complete digestive system
- Has a closed circulatory system
- Acoelomate
- Has proboscis

Proboscis

An extensible or retractable tubular feeding organ in invertebrate worms

Phylum Gastrotricha

Hairy bellies/hairybacks
Gastrorichs
~ 790 species

What are some characteristics of Phylum Gastroricha?

- Mostly living at bottoms of lakes or oceans
- Tiny worms (0.06-3mm)
- Cilia covering their ventral surface
- Colorless, simple body plan. Acoelomate

Phylum Cycliophora

Symbion pandora

What are some characteristics of Phylum Cycliophora?

- Found in mouth-parts of Norway lobsters
- Only one known species
- Tiny animals < .5mm
- Sac-like, jug shaped body. No coelom
- Reproduces both asexually by budding and sexually

Phylum Annelida

Segmented worms, earthworms, and leeches

What are some characteristics of Phylum Annelida?

- Segmentation
- Has coelom
- Has hydrostatic skeleton
- Has a nervous system
- Has a complete digestive system
- Has a closed circulatory system
- Has an excretory system (metanephridia)
- Has a muscular system
- Gas exchange through the skin
- Hermaphrodiates
- Trochophore larvae
- Has chaetae (setae)

Nervous system of Phylum Annelida

Has compound eyes and brain. Has ventral nerve cord

Metanephridia

Ciliated tubes or organs functional as primary units of excretory system found in invertebrates like annelids, arthropods, and molluscs

Muscular system of Phylum Annelida

Outer circular layer and an inner longitudinal layer

Chaetae (setae)

Bristles of chitin used for anchoring or locomotion

What are the three classes of Phylum Annelida?

Polychaeta, Oligochaeta, and Hirudinea

Class Polychaeta

Polychaetes

What are some characteristics of Class Polychaeta?

- Mostly marine
- Sessile or free-living
- Deposit or filter feeders
- Tentacles modified into filtering organs
- Have parapodia

Parapodia

A pair of flatten extensions in each segment of polychaeta worms for locomotion and gas exchange

Class Oligochaeta

Earthworms

What are some characteristics of Class Oligochaeta?

- Mostly terrestrial
- Sparse chaetae
- Lack parapodia
- Has clitellum
- Feeds on detritus
- No eyes
- Hermaphroditic

Clitellum

Thickened, reproductive non-segmented region found in both earthworms and leeches

Class Hirudinea

Leeches

What are some characteristics of Class Hirudinea?

- Mostly freshwater
- Size range (1-30 cm)
- No parapodia
- Hematophagy
- Parasites, predators, and scavengers

Hematophagy

Blood feeding

What are the two clades of Annelida?

Errantia and Sedentaria

Errantia

Errantians
Mobile marine free-living annelids

What are some characteristics of Errantia?

- Mobile swimmers, crawlers, or burrowers
- Other are relatively immobile tube-dwellers
- Have well-developed jaws used for predation or grazing on multicellular algae
- Has pair of paddle- or ridge-like parapodia on each body segment

Sedentaria

Sedentarians
Less mobile annelids

What are some characteristics of Sedentaria?

- Burrower or tube-dwellers
- Includes earthworms and leeches

Phylum Sipuncula

Peanut worms

What are some characteristics of Sipuncula?

- Found in shallow water
- Soft, unsegmented body
- Coelom
- Deposit feeders, retractable feeding organ
- Has subgroups of Annelida

Phylum (?) Echiura

Spoon worms

What are some characteristics of Phylum Echiura?

- Found in marine
- Have proboscis
- Unsegmented body
- Deposit feeders
- Feeds with a large flattened spoon-like proboscis
- Closely related to Annelida

Phylum Mollusca

Mollusks
~ 93,000 species

What are some characteristics of Phylum Mollusca?

- Most are marine
- Has a body shell
- Has a soft body, mantle, and CaCO3 shell
- Has a radula
- Body plan has 3 parts: muscular foot, visceral mass, and mantle
- Digestive, excretory, circulatory, and reproductive systems

What are some Phylum Mollusca animals?

Chitons, snails, slugs, oysters, clams, octopuses, squids...

Body shell of Phylum Mollusca

The soft body of many species that is surrounded by a protective calcium carbonate shell

Radula

A ribbon-like feeding tissue with teeth (rasping "tongue") which is made up of chitin found in mollusks

Muscular foot

Used for locomotion, predation, and attachment

Visceral mass

The central section of a mollusk's body that contains the most of the mollusk's internal organs

Digestive system of Phylum Mollusca

More complicated. Complete with separated mouth and anus. Has radula

Excretory system of Phylum Mollusca

Efficient and uses nephridia

Circulatory system of Phylum Mollusca

Most have an open system

Reproductive system of mollusca

Trochophore and veliger

Veliger

The final larval stage of certain mollusks, having two ciliated flaps for swimming and feeding

Mantle

A thin layer of tissue which can secrete the shell. Has a mantle cavity and shell

What are four classes of Mollusca to know for the test?

Gastropoda, Cephalopoda, Polyplacophora, Bivalva

Valve

Another name for shell

Class Gastropoda

Snails and slugs
~ 70,000 species

What are some characteristics of Class Gastropoda?

- Mostly marine
- Twisted gut - torsion
- Spiral shell or no shell (slugs)
- Mobile herbivores and predators

Torsion in Class Gastropoda

A twisting of the body over on itself

Class Polyplacophora

Chitons
~ 1000 species

What are some characteristics of Class Polyplacophora?

- Mostly marine
- No torsion
- Segmented shell (8 shell plates)
- Flat shape, reduced head
- Has large, flat foot

Class Bivalvia

Clams, oysters, mussels, and scallops
~ 20,000 species

What are some characteristics of Class Bivalvia?

- Mostly marine
- Filter feeder
- Body is enclosed in valves, no head
- Lacks radula
- Clams have siphons for feeding
- Most have a strong muscular foot
- Some have eyes and sensory tentacles along the edge of their mantle
- Crystalline style