Phylum Arthropoda

Characteristics About 1 million species known, mostly marine About 1 million species known, mostly marine Artho- means joint/ pod means footed Artho- means joint/ pod means footed Most marine species are in a group of arthropods called crustaceans Most marine species are in a group of arthropods called crustaceans About 75% of all animals on earth are arthropods About 75% of all animals on earth are arthropods Specialized eye & sensory organs- wide angle of vision Specialized eye & sensory organs- wide angle of vision Specialized respiratory structures, gills, used for gas exchange Specialized respiratory structures, gills, used for gas exchange Some are filter feeders, some scavengers, others carnivores Some are filter feeders, some scavengers, others carnivores

Chitin exoskeleton- hard, but light and moderately flexible Chitin exoskeleton- hard, but light and moderately flexible The skeleton is external The skeleton is external Molting = an arthropod shedding the shell to be able to grow. There is a soft new shell underneath. Molting = an arthropod shedding the shell to be able to grow. There is a soft new shell underneath. Jointed appendages Jointed appendages Divided into sections: head, thorax, and abdomen Divided into sections: head, thorax, and abdomen Specialized segmentation- segments combined for specific functions Specialized segmentation- segments combined for specific functions

Reproduction Male transfers sperm directly to female to ensure reproductive success Male transfers sperm directly to female to ensure reproductive success In some species, female will house eggs for a time until they are further developed In some species, female will house eggs for a time until they are further developed Females can store sperm for fertilization at a later time Females can store sperm for fertilization at a later time Many arthropods have complex behaviors including mating rituals Many arthropods have complex behaviors including mating rituals

Crustaceans Types of Marine Arthropods: Types of Marine Arthropods: Subphylum Crustacea Subphylum Crustacea –68,000 species –2 pairs antennae –Gills for respiration –Head and thorax fused into a single unit called a cephalothorax; entire external body is called the carapace –Large array of appendages specialized for different functions; ex: pinchers on crabs, swimmerettes on the underside of shrimp hold developing eggs, etc.

Horseshoe Crabs Types of Marine Arthropods: Types of Marine Arthropods: Class Merostomata Class Merostomata –5 pairs of legs, first pair modified in males for reproduction –Females larger than males –Mating pairs come onto beaches each spring to breed and lay their eggs in wet sand –Among the oldest creatures on earth –They live and borrow in soft sediments, normally near shore where they feed on other invertebrates and scavenge.

Sea Spiders Types of Marine Arthropods Types of Marine Arthropods Class Pycnogonida Class Pycnogonida –Four or more pairs of jointed legs –Not insects or true spiders –Possess a mouth and proboscis for feeding –Mainly feed on sea anemones and hydrozoans (they are voracious predators!) –More common in cold waters, but can be found worldwide

Insects Types of Marine Arthropods Types of Marine Arthropods Class Insecta: Class Insecta: –Very few marine insects exist –Many insects feed in the intertidal zone at low tide, but these are just temporary visitors

 Class: Malacostraca  Order: Stomatopoda

Eyes -

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