Flashcards in Lecture 6 Deck (12):
What are the evolutionary features of the annelida?
There are about 15000 species
Have a trophophore larva like molluscs and are similar to the pilidium larva of nemertea
What are the ecological features of the annelida?
Occupy a wide range of habitats including marine, fresh water and damp soil and can be free living, parasitic or sessile
What are the basic body features of the annelids?
They have a true coelom (which unlike lophophorates and molluscs is not reduced)
They are segmented, including division of the coelom by septa
Septa are only penetrated by gut, blood vessels and nerves
What are the features of the digestive system of annelids?
Contains a mouth, muscular pharynx, oesophagus, crop, gizzard, intestine and anus
What type of blood system do annelids have?
A closed blood system consisting of a dorsal vessel, ventral vessel, connecting pairs of segmental vessels, no heart but blood is pumped by muscular dorsal vessel and 5 pairs of pumping vessels surrounding the anterior gut
What are the features of the nervous system of the annelids?
A paired or fused ventral nerve cord with segmental ganglia, a cerebral ganglion and a subpharyngeal ganglion
What are the features of the reproductive features of the annelids?
Most are hermaphrodites and use the clitellum to produce a mucous cocoon to pick up eggs and received sperm
This cocoon will reside in the soil while the embryo develops
How does the lophotrochozoa get its name?
Lopho from the lophophore in the the lophophorate phyla
Trocho from trochophore larva in nemertea, annelids and molluscs
What are the differences between the lophotochozoa and the ecdysozoa?
While there are no particular features to group the lophotochozoa the ecdysozoa all periodically moult
What are the evolutiuonary and ecological features of the nematoda?
There is about 90000 known species living in habitats including marine and freshwater environments they can often be important parasites and are ecologically important as they play a role in decomposition and nutrient cycling
What are the form and function features of the nematoda?
Have cylindrical bodies are unsegmented and covered by a tough cuticle
They have a complete gut (mouth, pharynx, intestines, anus)
Lack a circulatory or respiratory system as nutrients are transported in the pseudocoelom