BIOL 111 Lecture Notes - Lecture 50: Hirudo Medicinalis, Oligochaeta, Leech
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BIOL 111 – Organismal Biology
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o!Oligochaetes
!!oligochaete = “few hairs”
!!they have a few ventral setae, which they use for locomotion and
gripping during copulation
!!they are detritivores (helps aerate the soil)
!!e.g. earthworms
o!Leeches (Hirudinea)
!!are parasitic or predatory
•!drink blood from other animals
!!are mainly freshwater, although some are terrestrial
!!they have no setae
•!instead they have anterior and posterior suckers that can help in
locomotion and grabbing onto the host
!!leeches are hermaphroditic (but do not self-fertilize)
!!there is no larval stage
!!they can be used for medicinal purpose
•!clearing blood clots in surgery
•!certain anaesthetics and anti-coagulants can be extracted
!!e.g. Hirudo medicinalis
•!Reproduction
o!polychaetes are broadcast spawners
!!this is because polychaetes live in tubes and are sessile
o!terrestrial annelids have external fertilization using mucus
o!oligochaetes are hermaphroditic
!!their clitellum secretes a mucus cocoon for embryo development
!!they have no larval stage