diff --git a/animals.lisp b/animals.lisp
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+;;;;
+;;;; Terra Nostra is a Minecraft-like survival game for the commandline.
+;;;;
+;;;; This file defines animal and species structs and the various species
+;;;; found in-game.
+;;;; 
+;;;; (c) 2018 Daniel Vedder, MIT license
+;;;;
+
+(defstruct animal
+	(pos '(0 0))
+	(health 0)
+	(species NIL))
+
+;;TODO predatory species
+
+(defstruct species
+	(name "")
+	(strength 0)
+	(max-health 0)
+	(aggression 0) ;attack probability %
+	(group-size 1) ;maximum group size
+	(habitat '()) ;preferred biomes
+	(corpse-items '()))
+
+(let ((species-list NIL))
+	(defun register-species (symbol-name species-object)
+		(setf species-list
+			(cons (list symbol-name species-object) species-list)))
+
+	(defun get-species (symbol-name)
+		(cassoc symbol-name species-list)))
+
+(register-species 'deer
+	(make-species :name "deer"
+		:strength 3 :max-health 10 :aggression 0
+		:group-size 10
+		:habitat '(forest grassland)
+		:corpse-items NIL)) ;TODO
+
+(register-species 'boar
+	(make-species :name "boar"
+		:strength 7 :max-health 15 :aggression 5
+		:group-size 5
+		:habitat '(forest)
+		:corpse-items NIL)) ;TODO
+
+(register-species 'wolf
+	(make-species :name "wolf"
+		:strength 10 :max-health 20 :aggression 20
+		:group-size 6
+		:habitat '(grassland)
+		:corpse-items 'NIL)) ;TODO
+
+(register-species 'bear
+	(make-species :name "bear"
+		:strength 20 :max-health 30 :aggression 20
+		:group-size 1
+		:habitat '(forest)
+		:corpse-items 'NIL)) ;TODO