These two are both part of the Lophophorates which also include Phoronida, if I ever get a photo of a phoronid I'll be sure to add them to the list. All the members of these groups have food catching organs called (you guessed it) a lophophore. This is usually a circle or horseshoe shape around the mouth that is covered with cilia. The cilia are used to move water through the lophophore and that's how they catch plankton. These animals are also all sessile (they don't move) and secrete a protective covering. On Brachiopods the covering could be mistaken for a shell but technically its not produced in from a mantle like the shell of Mollusks .
Now here's a group that has at least some members that are common to all of use (we eat them). Mollusks all have a muscular "foot" and a mantle that usually secretes a shell. Your best to look at them in smaller classes. the first two I list here could also be referred to as gastropods.
Have only one part to their shell and include animals like snails and abalone.
In general these are like snails without shells (however some do have shells). Nudibranch means "nude gill" so much of the frills you see on a nudibranch are it's gills.
Have two parts to their shell and include such species as oysters and scallops.
These ones have shells made up of many (poly) plates (placo). They include animals like chitons which because of the multi-plate structure are very good at holding on to curved rocks.
Now this one is a bit of a stretch for the layman (of which I am one) but lets just say that the foot has evolved a lot into the arms and tentacles and the shell has disappeared or become internal on almost all cephalopods (squids and cuttlefish have internal pens or remnant shells) (the Nautilus still has a shell). This is one of my favourite groups and includes the largest mollusks by far (giant squid maybe 16 meters long).
This is another group that is known to many people (food again) these are the crabs. In general you can say that arthropods have an exoskeleton or a hard external shell. In B.C. we have 3 main groups of crabs:
These guys have 4 pairs of walking legs plus claws.
These crabs have 3 pairs of walking legs plus claws.
Although they have an exoskeleton it is softer and thus they tend to
use empty mollusk shells for protection. One species also uses empty tubeworm
tubes.
The odd ball of this group is the barnacle, think of him as a crab stuck
to the rock by his head and waving his feet in the air to catch food.
this group includes all anemones, jellyfish and corals. They are animals that have stinging cells and only one body opening (that is food comes in and waste leaves via the same opening). You can think of a jelly fish as an anemone floating upside down. Ctenophores are a small group of jellyfish like animals that are spherical or oval shaped (at present I have no photos up of this group).
This is the phylum porifera,, and its members can take many forms from huge barrels to tiny encrusting mats. They rank as the most primitive of multi-celled animals have no real tissues or organs. All members of the group are sessile (they don't move), in fact they were considered plants until 1765. Its hard to describe sponges in a few words, they could be flat, or bumpy, soft or hard, big or small and they live in all oceans.
These are the seastars and more, they often exhibit five sided symmetry
but in a significant number it is hard to see (without using a knife).
The seastars are common to us all but animals like sea cucumbers may not
be as common to many people. another good identifying characteristic of
echinoderms are tube feet. these are feet controlled by a separate water
vascular system in the animal. As you look at the photos here you will
see some animals that are hard to fit into this model but they do.