Seminar # 1:

Marine Invertebrate Classification

Standard ClassificationDeveloped by Carolus Linnaeus in the 18th centuryOrganizes organisms into groups and subgroups based on evolutionary relationshipsOften revised when new relationships are discovered (DNA evidence)

Example: Pseudocalanus spp.

Classification levels:Kingdom (broad)PhylumClassOrderFamilyGenusSpecies (specific)

Marine InvertebratesKingdom: AnimalMarine Invertebrates are those animals that do not have a backbone and include:

Phylum PoriferaPhylum CnidariaPhylum CtenophoraPhylum MolluscaPhylum AnnelidaPhylum ArthropodaPhylum BryzoaPhylum Echinodermata

Phylum Porifera (Sponges)Animals that form encrusting colonies that attach themselves to underwater objectsThey 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/floatingGelatinous body that is usually umbrella shaped or bell shapedThe tentacles of this phylum all have stinging cells

Examples of Phylum Cnidaria:

Phylum Ctenophora (non-stinging jellies)

Free swimming or floatingClear gelatinous bodies with rows of comb-like plates made of cilia (small hairs) that help to move the jelly aroundNo stinging cellsAlso called comb jellies

Examples of Phylum Ctenophora:

Phylum MolluscaFocus on Classes Gastropoda and BivalviaGastropods have a single shell (coiled or uncoiled)Bivalves have two shells (valves) joined by a hinge

Examples of Gastropods:

Examples of Bivalves:

Phylum AnnelidaFocus 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 ArthropodaFocus on Classes Merostomata and Crustacea“Joint-legged” with an external skeletonClass Merostomata = horseshoe crabs!Crustaceans are gill breathingPrimarily aquatic2 pairs of antennae and 4 or more pairs of legs and/or claws Includes zooplankton!!!

Examples of Merostomata:

Examples of Crustacea:

Phylum BryzoaHighly branched Can be calcified or soft Forms crusts that cover a surfaceTend 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 EchinodermataSpiny-skinned Usually rounded with bodies separated into 5 partsHave 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 invertebratesTheir larvae (young) start out like tadpoles with gills, a backbone, and a nerve cord…like usOften mistaken for sea anemonesIncludes tunicates and sea squirts

Examples of Phylum Chordata: