Kingdom Animalia
• Animals are multicellular, eukaryotic, heterotrophs whose cells lack cell walls. At some point in their development, animals can move (are motile).
• invertebrates—animals with no backbone or vertebral column
• Animals can carry out the following functions: feeding, respiration, circulation, excretion, response, movement, and reproduction.
Body Symmetry
• All animals have some type of symmetry EXCEPT SPONGES.
• radial symmetry: around a central point or axis (ex. sand dollar)
• bilateral symmetry: on two sides of a central plane (ex. butterfly)
• asymmetry: no symmetry (sponges)
Body Terms to Know
• anterior: front end
• posterior: back end
• dorsal: upper side
• ventral: lower side
• cephalization: concentration of sense organs and nerve cells at anterior (front) end of body
General Characteristics
• Porifera means “pore-bearing”
• Multicellular
• Two tissue layers
– Endoderm (inner layer)
– Ectoderm (outer layer)
– Mesenchyme – jellylike material between the layers
• Benthic
• Sessile
Injestion & Digestion
• Food particles and plankton enter ostia (pores)
• Ostia surrounded by pore cells
• Water and wastes exit through large opening, the osculum, at top of sponge
• Collar cells (choanocytes) beat flagella, coordinated movement causes water flow
• Collar cells trap food particles
• Passed to food vacuoles in amebocytes
• Digestion is intracellular - inside the cells
Gas Exchange
• Water coming through ostia contains dissolved oxygen
• Oxygen diffuses into cells in passing
• Carbon dioxide diffuses out
• Water with wastes exits osculum
Response to Stimuli
• Lack nervous system
• Myocytes – musclelike cells
• When myocytes contract, ostia close
• Possible protection from toxins in water
Reproduction (sexual)• Adult sponges release sperm and egg into
water
• Fertilized egg cell results from union
• Cell division occurs
• Morula forms (latin for raspberry)
• Blastula develops
• Blastula forms flagella, now called larvae
• Larvae exists as plankton until it makes contact with a substrate
• Attaches and grows into adult sponge
• Sponges can be male or female
• Hermaphrodites
– Produce sperm and eggs at different times to avoid self fertilization
Sponge Diversity
• Hardy creatures
• Found in variety of environments
• Unique spicules– Calcium carbonate
– Silicon dioxide
– Protein fibers, spongin
Piggy Nose Sponge, surrounded by encrusting sponge that typically grows on
dead areas of coral reefs