Unit 11 - Anthropods 1

Phylum

Versatile exoskeleton, Cuticle is protective and provides rigid muscle attachment sites. Soft areas provide flexibility. Metamerism

Tagmatization or tagmosis

Paired, jointed appendages, rigidity and joints impart strength and speed.

Complete, 3 part alimentary canal (foregut, midgut, hindgut) with several glands and compartments.

Versatile mandibles/fangs from modified paired appendages.

Gills in some, lungs in a few, tracheal system in some.

Open circulatory system, Hemocoel, heart with short open vessels circulate hemolymph.

Various excretory glands, Saccate nephridia in aquatic forms, Malpighian tubules in terrestrial forms.

Sac-like coelomic space functions as flitration end

Large and complex, 3 part brain with paired ventral nerve cords with segmented ganglia.

Simple eyes, have one lens that contains all the pigment cells. Compound eyes have multiple ommatidia each with their own lens and photoreceptive cells.

Trilobita, Chelicerata, Myriapoda, Crustracea, Hexapoda.

Body has 3 lobes (tagmata), cephalon, trunk, pygidium. 1 pair of antennae on cephalon.

2 tagmata, Cephalothorax (prosoma) and Abdomen (opisthosoma). 6 pairs of appendages on the cephalothorax, 1 pair of chelicerae, 1 pair of pedipalps, 4 pairs of walking legs. No antennae.

Phylum Anthropoda, Subphylum Chelicerata, Class Merostomata.

Prosoma has large carapace, Opisthosoma has long telson. Book gills.

Phylum Anthropoda, Subphylum Chelicerata, Class Pycnogonida.

Proboscis used to suck fluids from soft bodied organisms, digestive tract and gonads extend to the legs.

Phylum Anthropoda, Subphylum Chelicerata, Class Arachnida, Order Araneae.

Book lungs

Silk glands and spinnerets, used for egg protection, ballooning and lining home walls.

Araneae, Scorpiones, Opiliones, Acari,

Viviparous, Large pedipalps are pincers, abdomen subdivided into pre abdomen and post abdomen. Post abdomen has stinger.

Harvestmen, not venomous, has no fangs, chelicerae are small and pincerlike.

Complete fusion of cephalothorax and abdomen. Mites and ticks

Myriapoda, Chilopoda, Diplopoda.

1 pair of legs per segment, have unique forcipules (first trunk appendages modified into fangs).

2 pairs of legs per diplosegment, detrivores, heavily calcfied exoskeleton.

2 pairs of legs per diplosegment, detrivores, heavily calcfied exoskeleton.