Seminar # 1: Marine Invertebrate Classification

Standard Classification Developed by Carolus Linnaeus in the 18 th century Organizes organisms into groups and subgroups based on evolutionary relationships Often revised when new relationships are discovered (DNA evidence) Example: Pseudocalanus spp.

Classification levels: Kingdom (broad) Phylum Class Order Family Genus Species (specific)

Marine Invertebrates Kingdom: Animal Marine Invertebrates are those animals that do not have a backbone and include: Phylum Porifera Phylum Cnidaria Phylum Ctenophora Phylum Mollusca Phylum Annelida Phylum Arthropoda Phylum Bryzoa Phylum Echinodermata

Phylum Porifera (Sponges) Animals that form encrusting colonies that attach themselves to underwater objects They have a porous structure (Spongebob Squarepants is an example) Seawater is pumped through its body by flagella (microscopic filaments) Body is supported by a skeletal framework composed of tiny needlelike structures called spicules

Examples of Phylum Porifera:

Phylum Cnidaria (stinging jellies) Either attached to an underwater object or free swimming/floating Gelatinous body that is usually umbrella shaped or bell shaped The tentacles of this phylum all have stinging cells

Examples of Phylum Cnidaria:

Phylum Ctenophora (non- stinging jellies) Free swimming or floating Clear gelatinous bodies with rows of comb-like plates made of cilia (small hairs) that help to move the jelly around No stinging cells Also called comb jellies

Examples of Phylum Ctenophora:

Phylum Mollusca Focus on Classes Gastropoda and Bivalvia Gastropods have a single shell (coiled or uncoiled) Bivalves have two shells (valves) joined by a hinge

Examples of Gastropods:

Examples of Bivalves:

Phylum Annelida Focus on Class Polychaeta (Under the microscope these look like worms with a walrus beard) Sometimes hard to identify (some require a microscope to distinguish) Worms that are segmented (divided into ring-like sections) and have bristles (setae) on each segment

Examples of Phylum Annelida:

Phylum Arthropoda Focus on Classes Merostomata and Crustacea “Joint-legged” with an external skeleton Class Merostomata = horseshoe crabs! Crustaceans are gill breathing Primarily aquatic 2 pairs of antennae and 4 or more pairs of legs and/or claws Includes zooplankton!!!

Examples of Merostomata:

Examples of Crustacea:

Phylum Bryzoa Highly branched Can be calcified or soft Forms crusts that cover a surface Tend to be a common fouling organism (meaning it grows on boat hulls, mooring lines, pilings, lobster pots, and other hard objects)

Examples of Phylum Bryzoa:

Phylum Echinodermata Spiny-skinned Usually rounded with bodies separated into 5 parts Have been known to scrub the sea floor of all organisms (some are extremely predatory) Includes sea urchins, sand dollars, sea stars, and sea cucumbers

Examples of Phylum Echinodermata:

Phylum Chordata (not invertebrates!) Bag-like creatures often mistaken for invertebrates Their larvae (young) start out like tadpoles with gills, a backbone, and a nerve cord…like us Often mistaken for sea anemones Includes tunicates and sea squirts

Examples of Phylum Chordata: