Annelida Flashcards
What are segmented worms, found in marine, freshwater, and moist terrestrial habitats, have a trochophore larva?
Annelids
What is true segmentation also known as?
Metamerism
What are the segments that contain repeated external and internal morphological features called?
Annuli
For annelids, except species, what do each segment have that aid in movement?
Chaetae/setae
What is the anchor segment in annelids?
Short setae
What is the segment that aid in swimming in aquatic forms in annelids?
Long setae
What is the body plan of typical annelids?
2 part head, segmented body, terminal portion
What is the terminal portion also called as and contains the anus?
pygmidium
what are the parts of the head?
prostomium and peristomium
Are the head and pygmidium considered segments?
No
Where are older segments found in annelids?
Anterior end
What kind of ceolom do all annelids have?
true coelom
How does the coelom form in annelids?
Schizocoely
What prevent movement of fluids between segments in annelids?
Septa
What kind of muscles is the body wall surrouding the coelom made of?
Circular and longitudinal
In most annelids, what does that fluid filled coelom serve as?
Hydrostatic skeleton
Do annelids have a complete digestive system?
Yes
What help facilitate excretion in annelids?
Nephridia
How is gas exchange facilitated in annelids?
Through skin, gills or pparapodia
What kind of hearts do annelids have?
Aortic arches
Describe the nervous system of annelids
2 ventral nerve cords and nerve ring around pharynx
What is the brain made of?
Pair of dorsal ganglia
Are annelids monoecious or dioecious
can be either
What do monoecious annelids have?
Permanent gonads
What do dioecious annelids have?
temporary gonads
How does asexual reproduction occur in annelids?
fission and fragmentation, can regenerate
What 2 historical classes are paraphyletic?
Polychaeta and Oligochata
What polychaeta are mostly marine, have multiple setae per segment?
Errantia
In errantia, what are the fleshy appendages each segment has and are primary respiratory organs called?
Parapodia
What are errantia usually?
Predators or scavengers
Do errantia have permanent sex organs?
No, temporary gonads
What group of annelids contain sedentary polychaetes and oligochaetes that live in tubes or burrows and also include clade clitellata?
sedentaria
What differentiates sedentaria from errantia?
have tentacles around head for feeding and respiration
What sedentaria have fewer, reduced chaetae or no chaetae, earthworms and leeches?
Clade clitellata
What do clitellata contain that is a ring structrue that secretes mucus for reproduction and is always visibile in mature oligochaetes but is only visible in leeches during mating season?
Clitellum
Are clade clitellata monoecious or dioecious?
Monoecious
How do clade clitellata develop?
Direct; inside cocoon
What annelid historical class are paraphyletic, most are terrestrial or freshwater with a few parasitic, marine, and brackish forms and setae are less numerous than in polychaetes?
Oligochaetes
What do oligochaeta lack?
Parapodia
Are oligochaeta scavengers or predators?
Scavengers
In oligochaeta what reduce the concentration of calcium ions in the blood and regulate acid-base balance?
Calciferous glands
In oligochaeta where is the food stored in?
crop
In oligochaeta where is the food passed on for grinding into small pieces?
gizzard
What is the infolding structure in the small intestine of oligochaeta that increases surface area?
typhlosole
In oligochaeta does circulation and respiration take place?
double transport system
gas exchange in oligochaeta is what?
Cutaneous
What is contained in the first 3 segments and the final one in oligochaeta?
Paired metanephridia
What is the difference with what aquatic and terrestrial polychaetas excrete?
Ammonia; urea, respectively
What are the large axons in oligochaeta that increase rate of conduction called?
giant axons
Do oligochaeta have eyes?
No
What do earthworms primarily rely on?
chemical and tactile signals
Are oligochaeta monoecious or dioecious?
monoecious
In oligochatea reproduction, what keep the worms together and what penetrates?
mucus from clitellum; modified setae
Why are earthworms helpful?
mixes topsoil and subsoil, produce nitrogenous products
What annelid historical class are true leeches, completely lack setae, have exactly 34 segments, mostly freshwater, many are carnivores, some are parasites?
Order Hirudinea
Do leeches have distinct coelomic compartments?
No
What does the reduced coelom in leeches filled with?
Connective tissue and lacunae
Are leeches predators or scavengers?
Both
What do leches feed on?
tissue fluid; blood
What help leeches cut through skin?
Chitinous jaws and anaesthetic and anticoagulant salivary glands
What are leeches used for?
Bloodletting and modern medicine
How many brains do leeches have?
2
In the brain of leeches, what has 6 pairs fused ganglia?
Anterior
In the brain of leeches, what has 7 pairs?
Posterior
Are leeches monoecious or dioecious?
monoecious
How do leeches reproduce?
Cross-fertilization; sperm transferred by hypodermic impregnation
How do leeches circulate?
Some have oligochaete circulatory system, others rely on coelomic sinuses
