Invertebrates 1
Porifera (Sponges)
Hermaphrodites
Filter Feeders
Mobility
Several different types of cells
Lack true tissues, but have cells with specialized functions
can swim as larvae
plant themselves down as adults
flows out through larger opening (osculum)
draws water into central cavity (spongocoel)
resulting zygote is flagellated and swims to disperse from parent
cross fertilization can occur when sperm is released into water current
Sponge layers separated by mesophyll between the outer skin layers. Both layers in contact with water aids gas and water exchange
Amoebocytes move through mesophyll and preform many functions
Flagellated Choanocytes line the spongocoel, engulf food particles by phagocytosis
Cnidaria
Tentacles
Medusozoa
Basic Body Plan
Anthozoans
Have tissues
Medusa
single opening (both mouth and anus)
Polyps
Gastrovascular cavity
largely sessile
sea anemones
cup right side up
moves freely in water
either passive drifting or contractions of cavity
jelly-fish type shape
contain cnidae--> capsulized organelles that can shoot outward towards prey. Some have stingers
Contains cnidocytes
Hydrozoans: alternate between polyp and medusa
Scyphozoans and cubozoans: spend majority of life in medusa stage
alll cnidarians that produce a medusa
Polyp stage more conspicuous
Hydras only exist in polyp form
many species secrete a hard exoskeleton of calcium carbonate
build on remains of previous generations
Occur only as polyps
Lophotrochozoans
Platyhelminthes, Rotifers and Acanthocephalans, Lophophorates, Molluscs, Annelids
Bilaterians
Platyhelminthes
Most have gastrovascular opening with only 1 hole
No organs for gas exchange, metobolic processes by diffusion because cells so close to water
No circulatory system--> oxygen moved through body through diffusion/gas exchange
Acoelomate with 3 germ layers
2 major life forms
Flatworms with dorsally flattened bodies
Parasitic flatworms (tapeworms)
Free-living flatworms (Planarians)
hermaphrodites
asexual reproduction through fission (cut one in half, tissue regeneration, 2 planarians!)
light sensitive eyespots that can see outlines, not details
suckers/hooks to attach to host intestines
no gastrovascular cavity at all--> no mouth--> absorb nutrients across body surface
adults inhabit vertebrates
Mollusca
General body plan
Most have separate sexes--> some are hermaphrodites
Gastropods
Soft bodied coelomates
mantle: secretes shell, layer of tissue between visceral mass and shell.
visceral mass: holds internal organs
radula: curved teeth for feeding
foot: helps them move around
Bivalves
Cephalopods
General Characteristics
Head with eyes on tentacles
use radula to graze algae (herbivores) or bore holes (carnivores)
Aquatic gastropods have gills, terrestrial use lining of lungs for gas exchange
most have single spiral shell
no distinct head, no radula
mantle cavity contains gills for feeding and gas exchange
shell laterally divided into two hinged halves
some have eyes and sensory tentacles along outer edge of mantle
all aquatic (think clams and oysters)
Shell reduced or internal
closed circulatory system
water expelled from mantle cavity for movement
Well developed sensory organs (like a brain)
Marine predators that use tentacles to grasp prey
eyes are extremely similar to human eyes
unusual body plan: body, head, then legs
Annelida
Sedentarians: more sessile than errantia, burrow slowly through sediments or soil, some live within tubes to protect their body, leeches and earthworms
Errantians: most mobile, many predators, each body segment has a paddle-like appendage
Earthworms are decomposers
Segmented coelomate worms that live in freshwater, marine, and in damp soil