Phylum Arthropoda: Subphylum Crustacea, Class Maxillopoda, Sublass Thecostraca

1. Subphylum Crustacea, Class
Maxillopoda, Sublass Thecostraca

2. Balanus (Barnacles)
Balanus
Exclusively marine
Shallow and tidal
waters
Roughly circular

3. Balanus (Barnacles)
Sessile
Filter-feeders
Encrusters
Shells composed of calcite
Most are hermaphroditic

7. Balanus (Barnacles)
Life Cycle
Fertilized
egg
Nauplius Cyprid
Adult

8. Nauplius

9. Cyprid

10. 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

11. Balanus glandula

12. Balanus (Barnacles)
2. Balanus crenatus
(Crenate barnacle)
-flat & white
-attaches to discarded
bottles and other debris

13. Balanus crenatus

14. Balanus crenatus

15. 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.

16. Balanus nubilus

17. Balanus nubilus

18. Balanus (Barnacles)
4. Pollicipes polymerus
(Gooseneck barnacle)
-dense colonies on shallow,
current swept reefs and walls
-exterior shell covered with
distinctive white plates

19. Pollicipes polymerus

20. Pollicipes polymerus