Zoology Annelids Part 2

What kind or worms are included in Class Siboglinidae

What kind or worms are included in Class Siboglinidae

Pognophorans and Bearworms

Class Siboglinidae general fact

• 150 species

• most < 1 mm in diameter

• giant beardworms live in hydrothermal vents (3m long, 5 cm in diameter

• most live in mud depths of 10,000 m

How do class Siboglinidae get their nutrients if they are living in the vents

they are chemoautotrophs, and extract sulfur compounds from the vents that they live in

What kind of tubes do some Siboglinidae dwell in

they secrete and live in long chitonous tubes, 3x-4x length of animal

Class Siboglinidae body details

• short anterior forepart, a long slender trunk and small, segmented opisthosoma

• tentacles on a cephalic lobe to gather food

• no mouth or digestive tract: nutrients are absorbed via tentacles

what kind of relationship will a organism from Class Siboglinidae have in order to gain nutrients

they form mutualistic relationships with chemoautotrophic bacteria in order to gain their energy

What kind of sexes are present in class siboglinidae

the sexes are separate

What is unique about the reproduction of classes found in the clade Clitellata?

they have reproductive structures called clitellum

Clitellum visual description

ring of secretory cells found in a band around the worm body

How does clitellum present itself in the two classses: Oligochaeta and Hirudinia?

They are permanent in Oligochaeta, and seasonal in leaches

What kind of sex do Clitella exhibit

they are hermaphrodies: both organisms involved in mating can potentially leave pregnant

How does the cocoon of Clitellata work (simplified)

• young develop inside the cocoon that is excreted by the clitttelum

• the young will emerge from the cocoon as small little worms

Class Oligochaeta general fact

• 3,000 species

• soil to freshwater, few marine or parasitic

• fewer setae than polychaetes

How do class Oligochaeta live and eat?

• burrow in moist soil, live in branched connected tunnels

• scavengers, feeding on decayed oganic matter

Class Oligochaeta: Circulation and respiration

• blood circulates in a closed system running lengthwise in the body

• blood: colorless dissolved in hemoglobbin

• gas exchange across body surface

Class Oligochaeta: Nervous system

• Neurosecretory cells in brain: secrete neurohormones

How do neurohormones affect the Oligochaeta

• regulate reproduction, secondary sex characteristics, regeneration

• photoreceptors in epidermis, stray away from light (negative phototaxis)

Class Oligochaeta: Reproduction

• monoecious

• sperm produced by testes

• fertilization and ebryogeneiss occur in cocoon

• regeneration depends on species and the extent of damage

Australian Oligochaeta

Giant Gippsland Earthworm

• approx 1 m length

• cocoon: 4-7 cm

Class Hirudinida general fact

• 600 species

• most freshwater, few marine or moist terrestrial

• vary in color, flattened

• some carinivores (eat small vertebrates)

  • fixed number of segments!

How do Hirudinida move around

suckers for attachment and they “inchworm” along surfaces

What is Hirudinida gut specialized for

gut is specialized for the storage of blood

3 orders that Hirudinea are divided into

Order Hirudinia (true leeches)

Order Acanthobdelidae

Order Branchiobdellidae

Order Hirudinea Description

• 34 segments

• Lack setae

• 2 top and bottom suckers (posterior and anterior suckers)

Order Acanthobdellidae Description

• 27 segments

• setae only present on first five segments

• only posterior suckers

Order Branchiobdellidae Description

• 14-15 segments

• lack setae

• only anterior sucker

• commensal or parasitic only on crayfish