SOME EXAMPLES
STRUCTURE OF A SPONGES; let's draw one!
VITAL FUNCTIONS IN PORIFERANS
Nutrition
They feed by filtration. Water enters by the pores and exits through the osculum.
Nutritive particles of water are caught by the cells that cover the atrium (choanocytes). These cells have a flagellum that is responsible for creating the water flow through the sponge.
Interaction
Poriferans haven't got neither sense organs nor nervous system..
Reproduction: they have asexual reproduction by fragmentation or budding, and sexual reproduction (ova and sperm).
To sum up
Let's see the different types!
All live in water (salty or fresh, it depends on the species).
Jellyfish are free-living organisms while corals and sea-anemonaes are sessiles.
Let's draw and see the parts of their bodies;
VITAL FUNCTIONS IN PORIFERANS
Nutrition
Most are carnivorous. They have a unique cells called cnidocytes which they use to capture their preys.
Cutaneous respiration.
Interaction
Nervous network.
Reproduction
Polyps have asexual reproduction by budding e.g. Hydra sp
Alternation of generations (sexual and asexual in the same cycle)
CHARACTERISTICS
They have bilateral symmetry.
Body worm-shaped, cilindrical and divided into rings (metameres).
See the examples
Draw the outside and look inside!
VITAL FUNCTIONS IN ANNELIDS
Nutrition;
Detritivores as the earth-worm.
Parasites as leeches.
Filter-feeders like Nereis.
Cutaneous respiration.
Gills.
Closed circulatory system.
Interaction; sense organs and nervous system.
Sexual reproduction; read and do a sum up of this vital function. Then, watch the video.
CLASS GASTROPODS (snails, slugs and limpets)
Body with;
head (2 pairs of tentacles).
mantle that contains the visceral mass and forms a shell.
Foot.
External body of a snail
Internal anatomy of a snail
Nutrition; gastropods have a unique structure in their mouths called radule. Let's see how it is!
Interaction;
gastropods have eyes and other sense organs (look their tentacles) and cerebral ganglia related to them.
Sexual reproduction.
Watch the video and complete all the information about their reproduction:
hermaphrodites or not;
type of fertilization;
type of embryonic development;
type of post-embryonic develpment.
CLASS bivalves (mussels, clams and oysters)
A shell with too jointed valves.
No head.
Foot in shape of asxe.
CLASS cephalopods (squids, octopus and cuttlefish)
To start with...😯
CHARACTERISTICS OF CEPHALOPODS
Head;
with tentacles to hunt their preys and a mouth with a beak-shaped jaws.
two big eyes.
Mantle covering all the body.
An inner shell (pen in the squids, cuttlebone in cuttlefish).
They have bilateral symmetry.
They have jointed appendages, such as legs, antennae and mouthparts.
They have a protective external skeleton or exoskeleton that enables the animal to move.