Subphylum Crustacea, Class Maxillopoda, Sublass Thecostraca

Balanus (Barnacles)

Balanus

Exclusively marine

Shallow and tidal waters

Roughly circular

Balanus (Barnacles)Sessile

Filter-feeders

Encrusters

Shells composed of calcite

Most are hermaphroditic

Balanus (Barnacles)Life Cycle

Fertilized egg

Nauplius Cyprid

Adult

Nauplius

Cyprid

Balanus (Barnacles)Representative species:

1. Balanus glandula (Common acorn barnacle)

-rugged white shell with a base that is not much wider than the top

-shallow rocky area

Balanus glandula

Balanus (Barnacles)

2. Balanus crenatus(Crenate barnacle)

-flat & white

-attaches to discarded bottles and other debris

Balanus crenatus

Balanus crenatus

Balanus (Barnacles)3. Balanus nubilus (Giant barnacle)

-Rugged white shell with two inner plates that close

-Can grow individually, but often seen in dense clusters growing on top of one another.

Balanus nubilus

Balanus nubilus

Balanus (Barnacles)4. Pollicipes polymerus(Gooseneck barnacle)

-dense colonies on shallow, current swept reefs and walls

-exterior shell covered with distinctive white plates

Pollicipes polymerus

Pollicipes polymerus