Porifera
What is a parazoan?
An organism that lacks true tissues
Cnidarians have what kind of symmetry?
Radial
Flatworms are classified as what type of coelomate?
Acoelomates
Annelids are characterized by which trait that allows specialization and repetition of body parts?
Segmentation
Trematodes, or flukes, typically require this in order to complete their life cycle
Intermediate host
Sponges are both male and female, making them this term.
Hermaphroditic
What are the two embryonic germ layers of cnidarians called?
ectoderm and endoderm
Non-parasitic platyhelminths have which type of digestive system?
Incomplete
This group of annelids includes earthworms
What percentage of animals are parasitic?
About 50%
What type of fertilization do sponges have?
Internal
What is the specialized stinging cell in cnidarians?
Cnidocyte
Tapeworms (Cestoda) lack which organ system entirely?
Digestive system
This annelid group includes bloodsucking ectoparasites sometimes used medicinally.
Leeches (Hirudinea)
A parasite that cannot live without its host is described as ______
Obligate
Sponges lack what developmental stage?
Gastrulation
What is the organelle within a cnidocyte that actually injects the sting?
Nematocyst
What is the head region of a tapeworm that bears hooks and suckers called?
Scolex
Marine polychaetes exchange gases using these structure
Parapodia
One ecological benefit of parasites is that they help prevent _______ in host populations
overpopulation
Sponges feed using this method, filtering particles from water.
Suspension feeding (filter feeding)
What type of fertilization do corals have?
External
What are the reproductive segments of a tapeworm called?
Proglottids
Annelids possess this type of body cavity, unlike flatworms
True coeloms
Eliminating a host species can have what effect on an obligate parasite?
Extinction