Arthropods 1

Arthropods are __% of all animal species

80

What are the three general segments of an arthropod body?

Head, Thorax, Abdomen

What is the exoskeleton made of in an arthropod?

Chiton

How do arthropods grow with a rigid exoskeleton?

Molting

What kind of symmetry do arthropods have?

Bilateral

What are Hexapods?

Subphylum of insects

What are Myriapods?

Subphylum of centipedes

What are Chelicerata?

Subphylum of arachnids and horseshoe crabs

How many antennae do Crustacenas have?

4

What are Crustaceans

Subphylum of mainly marine animals like isopods and crabs and lobsters

How many antennae do Hexapods have?

2

How many antennae do Myriapods have?

2

How many antennae do Chelicerata have?

0

How many legs do Crustaceans have?

variable, typically 10

How many legs do Hexapods have?

6

How many legs do Myriapods have?

A lot (centipedes and millipedes)

How many legs do Chelicerata have?

4-5 pairs of walking legs. First pair of legs are chelicera

What are Merostomata

Class of Chelicerata. Horseshoe crabs

What is the prosoma

Biggest region that contains the ‘head’ and appendages. Also called the cephalothorax

Horseshoe crabs

What is the carapace?

Covers/protects the prosoma and sometimes opisthoma

Horseshoe crabs

What is the opisthoma

The spined, segmented abdomen that contains the gills

Horseshoe crabs

What is the hinge?

Connects the prosoma and opisthoma

Horseshoe crabs

What are the book gills?

5 pairs, housed in branchial chambers, each contains over 100 lamellae where gas exchange occurs

Horseshoe crabs

What is the etnapophysis

Muscles that support the gills

Horseshoe crabs

What is the telson

The tail, used for locomotion and self-righting (can use it to flip themselves over if stuck on their back)

Horseshoe crabs

What are the lobes/ridges?

Help distinguish different segments

Horseshoe crabs

What is the gizzard?

Mechanically grinds food

Horseshoe crabs

What is the proventriculus?

Works with the crop to store food

Horseshoe crabs

What is the oscelli

Detects light, used to time spawning

Horseshoe crabs

What is the compound eye?

Forms images, used for navigation

Horseshoe crabs

What is the chelicera?

First appendage pair, used for handling food

Horseshoe crabs

What are the walking legs?

Used for walking lmao

Horseshoe crabs

What are the pedipalps?

The first pair of walking legs, in males, it has claspers for mating

Horseshoe crabs

What is the mouth?

Used for eating

Horseshoe crabs

What is the chilaria?

Flap-like appendages on the underside that help guide food towards the mouth

Horseshoe crabs

What is the gnathobase?

Jaw-like structures that help with grinding food

Horseshoe crabs

What are two ways horseshoe crabs are economically valuable?

Blood is used in medical field to test for E-coli and related bacteria

Used to be caught to be used as fertilized, but no longer, after the rize of chemical fertilizers

What is one way horseshoe crabs are ecologically useful

Vital food source for northward migrating shorebirds

What are larval horseshoe crabs called?

Trilobites

What is unique about sea spider reproduction?

Paired external fertilization. Once females release eggs, the male release sperm, catches fertilized eggs, and broods them on his legs.

What is the cephalon?

Head region

Sea spider

What is the chelicera?

Claw-like appendages on the cephalon used for halding prey

Sea spider

What is the proboscis?

Sucks up prey

Sea spider

What is the pedipalp?

Physical sensing of the environment

Sea spider

What are the ovigers?

Ovigerous legs. Pair of legs, usually found only in males, used to carry egg masses

Sea spider

What is the abdomen?

Hosts the anus

Sea spider

What is the oculur tubercule?

Hosts the eyes

Sea spider

What is the trunk?

The segmented body. In most species, there are 3-4 segments, each with a pair of legs, however, some deep-sea species have 5-6 segments, giving them 10-12 legs

Sea spider

How do sea spiders digest?

The gut extends into all legs, undergoes peristalsis to move gut materials around

How do sea spiders respirate?

No gills, lungs, or trachaea, instead, oxygen diffuses across cuticle of legs into blood

How do sea spiders circulate blood?

Their heart is small and weak. Blood pumped as the gut undergoes peristalsis

How do sea spiders store gonads?

Ovigers

What are Thecostracas

Class of crustaceans. Barnacles

How much of barnacles are free living and how much are parasitic?

1/3 parasitic, 2/3 free living

What are cirri?

Feeding and respiration appendages. Allow for reproduction and excretion. Modified legs.

Badnacles

Describe acorn barnacles

No peduncle, plates are cemented directly to the surface

Describe gooseneck barnacles

Softer flexible peduncle, which allows for movement anf for the capitulum to sway in the water

What is the capitulum in gooseneck barnacles?

The main body

What are cirri?

Six pairs of feathery limbs that are used for feeding and movement

Barnacles

What are cetae?

Sensory hairs that cover the cirri

Barnacles

What are plates?

Hard, protective outer calcium carbonate structures that close for protection and open to expose cirri

Barnacles

What are the two types of plates in barnacles?

Scutum and tergum

What are cement glands?

Secretes cement to attach the barnacle to a substrate

What is the peduncle?

Stalk-like structure in gooseneck barnacles that serves as an attachment to the substrate and hosts ovaries

What is the capitulum

The main body, seperate from the peduncle

Barnacles

What are antennae?

Initial, primary attachment, cement is secreted around the antennae to fortify attachment, come close to disappearing as the barnacle matures, absent in gooseneck barnacles

Describe the scutum plan

Bigger plates, anterior/dorsal side

Describe the tergum plan

Smaller plates, posterior/ventral side, a little more mobility

How do barnacles settle in terms of direction?

Head down, or dorsal side down, in the sediment