Annelida 2 Flashcards
Overview of classes
Cheatae, parapodia, and cephalic appendages
Polychaeta
Clitellata
Subclass: Oligochaeta
Subclass: Hirudinoidea
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Overview of class Polychaeta 3 points
- Generally marine
- Each body segment has a pair of fleshy protrusions called parapodia that bear many chaetae.
- Highly variable in morphology and habitat type, >10,000 species
Overview of class Clitellata 3 points
- Clitellum – important for reproduction.
- They comprise around 8,000 species.
- No parapodia and their heads are less developed heads
Chaetae
3 points
- Bundles of chitinous cylinders bound by protein
- Large degree of variation
Species-specific - Used for locomotion
Parapodia
4 points
- Unjointed, fleshy appendages
- Large degree of variation
Species-specific - Two elements: notopodium and neuropodium
- Used for locomotion and respiration
Cephalic appendages
4 points
- High diversity in cephalic appendages
- Palps
Grooved feeding palps
Sensory - Tentacle structure varies
- Provide information of feeding
Class: Polychaeta [key points]
- Segments bear chaetae (analogous to setae)
- Well developed parapodia
- Prostomium and peristomium bear pronounced sensory organs, and motile appendages
- Modified foregut
- Dioecious
Indirect development
Trochophore larva - Mostly marine
- 87 families in 25 orders
Class: Polychaeta
Order: Capitellidae; Family: Arenicolidae
7 points
- Lug worms or black lugs
- Thick fleshy bodies with simple heads
- Pharynx is unarmed and eversible
- Burrowers
- Deposit feeders, some graze on algae
- Interitadal and subtidal
- Excellent indicator species for pollution
Class: Polychaeta
Order: Phyllodocida
5points
- 4,600 species in 20 Families
- Variable size, can exceed 1 m
- Axial muscular proboscis
- Mostly errant with well-developed parapodia
- Prostomium with one or two pairs of eyes, dorsal pair of antennae and a pair of ventrally positioned sensory palps.
Class: Polychaeta
Order Phyllodocida; Family Nereididae
7 points
- Ragworms
- Burrowers in sand and mud
- Bioturbators
- Common in estuarine, coastal sites but also in deep sea
- Predators or scavengers but also feed on algae and microorganisms
- Numerous, highly vascularized parapodia
- Well-developed heads with two large pincer teeth
Class: Polychaeta
Order: Phyllodocida; Family Aphroditiformia
8 points
- Scaled Polychaetes known as the “scale worms”
- Short and dorsoventrally flattened
- Can reach 30cm in length and 15cm width (Eulagisca gigantea)
- Relatively few segments at adulthood.
- Covered in scales called elytra
- Can be active predators
- Eversible pharynx
- Commensal
Class: Polychaeta
Order: Sabellida
8 points
- 1200 species across 5 Families
- Heteronomous body form
- Huge size range from 3 to 2500 mm
- Mostly sedentary
- Tube-dwellers
- Ecosystem engineers
- Anterior end bears tentacular crown
- Suspension feeders
Class: Polychaeta
Order: Sabellida; Families: Sabillidae and Serpulidae
2 points
1. Sabellids Live in sediment Mucus tubes Radiolar crown or feathery palps Suspension feeder
2. Serpulids Calcareous tubes Usually attach to rocks Radiolar crown or feathery palps Suspension feeder
Class: Polychaeta
Order: Sabellida; Family: Siboglinidae
6 points
- Sedentary
- Chitin tubes
- Biogenic structures
- Host endosymbiotic bacteria
- Lack a mouth, anus and gut
- Chemosynthetic and organic rich habitats
Class: Polychaeta
Order: Sabellida; Family: Siboglinidae; Genus: Osedax
4 points
- Bone eating zombie worms
- Found only on long-submerged bones
- Between 50 and 100 microscopic dwarf males live inside a single female and never develop past the larval
- Osedax have colourful feathery plumes that act as gills
Class: Polychaeta
Order: Sabellida; Family: Siboglinidae; Genus: Osedax
3 points
- Osedax symbiotic bacteria digest the whale proteins and lipids.
- The Osedax secrete acid (rather than rely on teeth) to bore into bone to access the nutrients.
- Unusual root-like structures that absorb nutrients.
Class: Clitellata [key points]
6 points
- Chaetae reduced or absent
- No parapodia
- Prostomium and peristomium often lack pronounced sensory organs
- Clitellum
- Hermaphroditic
Complex reproductive system
Direct development - Marine, freshwater and terrestrial environments
Class: Clitellata
Sub-class: Oligochaeta
6 points
- Over 6,000 species in three orders with 25 families
- Chaetae reduced or absent
- Cephalic structures reduced
- Externally homonomous
- Clitellum
- Hermaphroditic
Class: Clitellata
Sub-class: Oligochaeta
Order Crassiclitellata
- Mainly terrestrial earthworms
- Over 3000 species
- Direct deposit feeders consuming live and dead organic matter
- Clitellum
Class: Clitellata
Sub-class: Oligochaeta
Order Haplotaxids
Family Naididae
5 points
- Mainly freshwater but includes marine and brackish
- 700 species
- Tube builders or burrowers
- Homonomous with a simple head
- Some reproduce asexually
Class: Clitellata
Sub-class: Oligochaeta
Order Haplotaxids
Family Enchytraeidae
3 points
- Mainly terrestrial with ~700 species but also marine
- Feed on bacteria, fungi and algae
- Mesenchytraeus solifugus thrives in glacial ice
Class: Clitellata
Sub-class: Hirudinoidea
- Around 500 species in three orders
- Body with fixed number of segments
- Chaetae reduced or absent
- Cephalic structures much reduced
- Suckers present on anterior and/or posterior
- Clitellum
- Leeches
Ectoparasitic, predators or scavengers
